Basics
292 technical concepts, organized by category. Find a topic and explore its prerequisites, explanation, and related concepts.
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- Networking
Ethernet
Ethernet provides local delivery between network interfaces.
Read topic → - Networking
Ethernet Switching
a switch learns where MAC addresses are and forwards local traffic accordingly.
Read topic → - Networking
IP
IP provides addressing and packet delivery across interconnected networks.
Read topic → - Networking
Subnets
the prefix tells a host which IP addresses belong to its network.
Read topic → - Networking
ARP
ARP maps a local IPv4 address to its MAC address.
Read topic → - Networking
Default Gateway
the default gateway is where a host sends packets when it doesn't know a more specific local route.
Read topic → - Networking
Routing
routing chooses the next step toward the destination.
Read topic → - Networking
Longest-Prefix Match
routers prefer the most specific known route to the destination.
Read topic → - Networking
ICMP
ICMP lets IP networks communicate errors and diagnostic information.
Read topic → - Networking
TTL
TTL prevents packets from living forever in a routing loop.
Read topic → - Networking
UDP
UDP provides minimal process-to-process delivery on top of IP.
Read topic → - Networking
Ports
IP identifies the host; ports help identify the communication endpoint/application.
Read topic → - Networking
TCP
TCP turns unreliable packet delivery into a reliable ordered connection.
Read topic → - Networking
TCP Flow Control
flow control prevents a sender from overwhelming the receiver.
Read topic → - Networking
TCP Congestion Control
flow control protects the receiver; congestion control protects the network.
Read topic → - Networking
MTU
MTU is the size limit imposed by the network carrying the IP packet.
Read topic → - Networking
MSS
MTU limits the IP packet; MSS limits the TCP payload inside it.
Read topic → - Networking
DNS
DNS separates human/stable naming from network addressing.
Read topic → - Networking
DHCP
DHCP automatically configures hosts joining an IP network.
Read topic → - Networking
NAT
many private hosts can share limited public IPv4 addresses.
Read topic → - Networking
VLAN
VLANs create separate logical LANs over shared switching infrastructure.
Read topic → - Networking
BGP
BGP lets independent networks exchange reachability while retaining control over their routing decisions.
Read topic → - Networking
Autonomous System
an AS is an independently administered routing domain on the Internet.
Read topic → - Networking
AS_PATH
AS_PATH records the inter-network path of a BGP route.
Read topic → - Identity and security
VPN
a VPN creates a private logical connection across an untrusted network.
Read topic → - Identity and security
IPsec
IPsec provides security directly at the network layer.
Read topic → - Identity and security
IKE
IPsec protects the traffic; IKE establishes the security relationship needed to do it.
Read topic → - Applications and APIs
HTTP
HTTP provides a standard request/response language for applications.
Read topic → - Applications and APIs
REST
REST uses HTTP around resources to create a simple, uniform application interface.
Read topic → - Applications and APIs
gRPC
gRPC makes remote service calls look like strongly typed operations with efficient transport.
Read topic → - Applications and APIs
WebSocket
WebSocket provides persistent two-way communication.
Read topic → - Applications and APIs
Webhooks
webhooks let one system notify another when an event occurs.
Read topic → - Applications and APIs
Reverse Proxy
a reverse proxy represents backend servers to clients.
Read topic → - Applications and APIs
Forward Proxy
a forward proxy represents clients to external servers.
Read topic → - Identity and security
OAuth2 Proxy
OAuth2 Proxy adds a login gate in front of an application.
Read topic → - Applications and APIs
Backend for Frontend (BFF)
a BFF adapts backend services to one frontend's needs.
Read topic → - Applications and APIs
Load Balancer
load balancing lets multiple machines serve one workload.
Read topic → - Identity and security
Encryption
encryption protects the confidentiality of information.
Read topic → - Identity and security
Symmetric Encryption
symmetric encryption uses shared secret key material for fast encryption.
Read topic → - Identity and security
Public-Key Cryptography
asymmetric cryptography separates public cryptographic information from a private secret.
Read topic → - Identity and security
Digital Signature
digital signatures provide integrity and proof that the signer possessed the private key.
Read topic → - Identity and security
Hashing
hashing creates a compact fingerprint of data.
Read topic → - Identity and security
Diffie–Hellman
Diffie–Hellman lets two parties establish shared secret material over an observable network.
Read topic → - Identity and security
Certificate
a certificate provides a signed binding between an identity and a public key.
Read topic → - Identity and security
Certificate Authority
a CA acts as a trusted issuer for certificate bindings.
Read topic → - Identity and security
PKI / Chain of Trust
PKI scales trust through certificate chains anchored in trusted roots.
Read topic → - Identity and security
TLS
TLS creates an authenticated, confidential and integrity-protected connection.
Read topic → - Identity and security
TLS Session Keys
the certificate can be shared publicly; traffic keys are connection-specific secrets.
Read topic → - Identity and security
Forward Secrecy
forward secrecy prevents later compromise of a long-term key from revealing past sessions.
Read topic → - Identity and security
mTLS
mTLS extends certificate authentication to both sides.
Read topic → - Identity and security
Authentication
authentication establishes who the system believes you are.
Read topic → - Identity and security
Authorization
authentication asks who are you? Authorization asks what may you do?
Read topic → - Identity and security
Password Hashing
servers should verify passwords without storing the original passwords.
Read topic → - Identity and security
SSO
SSO centralizes authentication across multiple applications.
Read topic → - Identity and security
OAuth 2.0
OAuth lets applications receive limited delegated access without receiving the user's password.
Read topic → - Identity and security
Access Token
an access token represents temporary authority to access a resource.
Read topic → - Identity and security
Refresh Token
refresh tokens allow short-lived access tokens without constant user authentication.
Read topic → - Identity and security
OpenID Connect
OAuth is primarily delegated authorization; OIDC adds standardized authentication.
Read topic → - Identity and security
JWT
JWT is a compact format for carrying verifiable claims between systems.
Read topic → - Identity and security
SAML
SAML enables federated identity, especially in enterprise browser-based SSO.
Read topic → - Identity and security
LDAP
LDAP provides a standard protocol for accessing directory information.
Read topic → - Identity and security
Kerberos
Kerberos enables centralized, ticket-based authentication across trusted network services.
Read topic → - Identity and security
SSH
SSH provides secure remote access over untrusted networks.
Read topic → - Identity and security
RBAC
RBAC assigns permissions through reusable roles rather than individually.
Read topic → - Identity and security
Least Privilege
minimize authority so mistakes and compromises have limited impact.
Read topic → - Identity and security
PIM / Just-in-Time Access
powerful privileges should exist only for the period in which they're needed.
Read topic → - Identity and security
Secret Manager / Key Vault
secrets should have their own protected lifecycle rather than living in source code.
Read topic → - Identity and security
Managed Identity
managed identities let Azure workloads authenticate without application-managed secrets.
Read topic → - Identity and security
Workload Identity Federation
federation replaces stored cross-system credentials with trust and short-lived tokens.
Read topic → - Computing fundamentals
Process
processes provide isolated execution environments for running programs.
Read topic → - Computing fundamentals
Thread
threads provide concurrent execution within a shared process.
Read topic → - Computing fundamentals
Virtual Memory
virtual memory gives processes isolated logical memory independent of physical RAM layout.
Read topic → - Computing fundamentals
File System
file systems organize persistent data and give applications a standard way to access it.
Read topic → - Computing fundamentals
System Call
system calls are the controlled boundary between applications and the operating-system kernel.
Read topic → - Computing fundamentals
Socket
a socket is an application's communication endpoint, used locally or across a network.
Read topic → - Computing fundamentals
Service / Daemon
services let the OS manage long-lived background applications.
Read topic → - Computing fundamentals
Virtual Machine
virtualization lets multiple isolated machines share one physical machine.
Read topic → - Containers and delivery
Container
containers provide lightweight application isolation without a separate kernel per application.
Read topic → - Containers and delivery
Container Image
an image packages a reproducible application environment.
Read topic → - Containers and delivery
Container Registry
a registry distributes versioned container images.
Read topic → - Containers and delivery
Kubernetes
Kubernetes continuously reconciles actual workloads toward declared desired state.
Read topic → - Containers and delivery
Kubernetes Pod
a pod is Kubernetes' basic unit of workload placement.
Read topic → - Containers and delivery
Kubernetes Deployment
Deployments manage replicated, updateable application workloads.
Read topic → - Containers and delivery
Kubernetes Service
Services separate stable service discovery from ephemeral pod identities.
Read topic → - Containers and delivery
Kubernetes ConfigMap
ConfigMaps separate environment-specific configuration from container images.
Read topic → - Containers and delivery
Kubernetes Secret
Kubernetes Secrets separate sensitive configuration from application images, though they still require proper cluster security and often integration with external secret stores.
Read topic → - Containers and delivery
Persistent Volume
persistent volumes separate durable data from ephemeral workloads.
Read topic → - Cloud and architecture
Cloud Computing
cloud computing turns computing infrastructure into an on-demand service.
Read topic → - Cloud and architecture
IaaS
IaaS gives you virtual infrastructure while the provider operates the physical layer.
Read topic → - Cloud and architecture
PaaS
PaaS removes much of the infrastructure and OS management from application teams.
Read topic → - Cloud and architecture
Serverless / Functions
serverless lets you execute code on demand without managing persistent servers.
Read topic → - Containers and delivery
Infrastructure as Code
IaC turns infrastructure configuration into reproducible, reviewable code.
Read topic → - Containers and delivery
Bicep / Terraform
declarative IaC describes the desired result rather than every manual provisioning step.
Read topic → - Containers and delivery
IaC Plan / What-If
planning separates understanding an infrastructure change from executing it.
Read topic → - Networking
VNet / Virtual Network
virtual networks bring private IP networking and segmentation into cloud infrastructure.
Read topic → - Networking
Subnet in the Cloud
subnets divide a larger network into manageable IP and security boundaries.
Read topic → - Identity and security
Private Endpoint / Private Link
Private Link-style technologies expose managed services privately inside your network.
Read topic → - Identity and security
Firewall
firewalls control which network traffic may cross a boundary.
Read topic → - Identity and security
WAF
a WAF applies security controls using application-layer knowledge.
Read topic → - Identity and security
Zero Trust
being inside a network should not automatically grant trust.
Read topic → - Applications and APIs
Message Queue
queues separate producing work from the immediate availability of the consumer.
Read topic → - Applications and APIs
Asynchronous Messaging
asynchronous communication separates the timing of producers and consumers.
Read topic → - Applications and APIs
Pub/Sub
pub/sub lets multiple independent consumers react to the same information.
Read topic → - Applications and APIs
AMQP
AMQP provides a standardized protocol for interoperable message-oriented systems.
Read topic → - Applications and APIs
Kafka
Kafka provides durable, scalable event streams that consumers can independently read and replay.
Read topic → - Applications and APIs
MQTT
MQTT provides lightweight messaging particularly suited to constrained devices and unreliable links.
Read topic → - Monitoring and reliability
Timeout
timeouts put a bound on how long a system waits for an uncertain dependency.
Read topic → - Monitoring and reliability
Retry
retries turn some transient failures into successful operations.
Read topic → - Monitoring and reliability
Exponential Backoff + Jitter
backoff and jitter prevent retries from amplifying an outage.
Read topic → - Applications and APIs
Idempotency
idempotency makes repeating an operation safe from unintended duplicate effects.
Read topic → - Monitoring and reliability
Circuit Breaker
a circuit breaker stops wasting resources on a dependency known to be failing.
Read topic → - Monitoring and reliability
Bulkhead
bulkheads prevent one failing dependency from exhausting shared resources.
Read topic → - Cloud and architecture
Distributed Transaction Problem
once state spans independent systems, atomic change becomes a distributed-systems problem.
Read topic → - Cloud and architecture
Saga
sagas handle distributed business operations through coordinated steps and compensation.
Read topic → - Cloud and architecture
Leader Election
leader election selects one coordinator among multiple nodes.
Read topic → - Cloud and architecture
Consensus
consensus lets distributed nodes reach reliable agreement without assuming every node is always available.
Read topic → - Networking
NTP
NTP keeps clocks across machines approximately synchronized.
Read topic → - Storage and databases
Relational Database
relational databases organize structured related data and provide powerful declarative querying.
Read topic → - Storage and databases
SQL
SQL is a declarative language for querying and manipulating relational data.
Read topic → - Storage and databases
Transaction
transactions make related database changes behave as one logical unit.
Read topic → - Storage and databases
Isolation
isolation protects transactions from problematic interference by concurrent transactions.
Read topic → - Storage and databases
Locking
locking coordinates concurrent access by temporarily restricting conflicting operations.
Read topic → - Storage and databases
MVCC
MVCC uses data versions to provide transactional views with greater concurrency.
Read topic → - Storage and databases
Index
indexes trade additional storage and write work for faster retrieval.
Read topic → - Storage and databases
Connection Pooling
connection pooling amortizes the cost of establishing database connections.
Read topic → - Storage and databases
Replication
replication maintains multiple copies of data for availability, durability or read scaling.
Read topic → - Storage and databases
Sharding
sharding scales by dividing data across independent storage nodes.
Read topic → - Storage and databases
Document Database
document databases store flexible structured objects rather than requiring one fixed relational shape.
Read topic → - Storage and databases
Cache
caching trades freshness and complexity for faster access and reduced backend work.
Read topic → - Storage and databases
Cache Invalidation
caching creates a second copy of data, so you need a strategy for when that copy stops being valid.
Read topic → - Storage and databases
Object Storage
object storage provides massively scalable storage for independently addressed blobs of data.
Read topic → - Storage and databases
SMB / NFS
SMB/NFS make remote shared storage accessible through file-oriented semantics.
Read topic → - Storage and databases
iSCSI
iSCSI provides remote block storage over IP.
Read topic → - Storage and databases
SFTP
SFTP provides secure remote file transfer over SSH.
Read topic → - Containers and delivery
Git
Git gives collaborative software development a versioned, mergeable history.
Read topic → - Containers and delivery
Branch
branches allow independent lines of development within the same repository.
Read topic → - Containers and delivery
Pull Request
pull requests create a controlled review boundary around code changes.
Read topic → - Containers and delivery
Continuous Integration
CI discovers integration problems soon after changes are made.
Read topic → - Containers and delivery
Continuous Delivery
continuous delivery keeps software in a state where it can be released reliably through automation.
Read topic → - Containers and delivery
Deployment Pipeline
deployment pipelines make environment promotion repeatable and controlled.
Read topic → - Containers and delivery
Artifact
immutable artifacts separate building software from deploying it and ensure environments receive the same build.
Read topic → - Containers and delivery
Blue-Green Deployment
blue-green deployment makes release switching and rollback largely a traffic-routing decision.
Read topic → - Containers and delivery
Canary Deployment
canary deployment limits the blast radius of a new release.
Read topic → - Applications and APIs
Feature Flag
feature flags separate deploying code from exposing behaviour.
Read topic → - Monitoring and reliability
Logging
logs preserve discrete events so past system behaviour can be investigated.
Read topic → - Monitoring and reliability
Metrics
metrics summarize system behaviour numerically over time.
Read topic → - Monitoring and reliability
Distributed Tracing
tracing reconstructs one operation across distributed components.
Read topic → - Monitoring and reliability
Correlation ID
a correlation ID links events belonging to the same logical operation.
Read topic → - Monitoring and reliability
OpenTelemetry
OpenTelemetry standardizes how applications produce and export observability data.
Read topic → - Monitoring and reliability
Health Check
health checks let infrastructure determine whether a workload is functioning.
Read topic → - Monitoring and reliability
Readiness Check
readiness tells infrastructure whether a running workload should receive traffic.
Read topic → - Monitoring and reliability
Alerting
alerting turns important telemetry conditions into human attention.
Read topic → - Monitoring and reliability
SLI
an SLI turns an aspect of service reliability into something measurable.
Read topic → - Monitoring and reliability
SLO
an SLO defines the desired level of measured service reliability.
Read topic → - Cloud and architecture
Horizontal Scaling
horizontal scaling increases capacity by adding machines or instances.
Read topic → - Monitoring and reliability
Rate Limiting
rate limiting protects shared capacity by controlling request frequency.
Read topic → - Cloud and architecture
Redundancy
redundancy removes dependence on a single component.
Read topic → - Cloud and architecture
Availability Zone
zones protect against failures affecting an entire facility or local infrastructure domain.
Read topic → - Cloud and architecture
Multi-Region Architecture
multi-region architecture addresses failures larger than a single region.
Read topic → - Storage and databases
Backup
replication protects availability; backups let you recover lost or corrupted historical data.
Read topic → - Monitoring and reliability
Disaster Recovery
disaster recovery is the planned process for restoring service after catastrophic loss.
Read topic → - Monitoring and reliability
RPO
RPO answers how much recent data can we afford to lose?
Read topic → - Monitoring and reliability
RTO
RTO answers how long can the service remain unavailable?
Read topic → - Cloud and architecture
Modularity
modularity limits how much of a system must be understood or changed together.
Read topic → - Cloud and architecture
Dependency Inversion
important logic should depend on contracts rather than concrete infrastructure details.
Read topic → - Cloud and architecture
Clean / Onion / Hexagonal Architecture
isolate core business logic from changing external technologies.
Read topic → - Cloud and architecture
Microservices
microservices trade distributed-system complexity for stronger deployment and ownership boundaries.
Read topic → - Cloud and architecture
Domain-Driven Design
DDD models business concepts, rules, and boundaries in the software.
Read topic → - Cloud and architecture
Bounded Context
bounded contexts prevent different domain meanings from being forced into one model.
Read topic → - Cloud and architecture
CQRS
CQRS allows reads and writes to use different models when their needs genuinely differ.
Read topic → - Cloud and architecture
Event Sourcing
event sourcing stores state-changing facts rather than only the latest state.
Read topic → - Applications and APIs
API Gateway
an API gateway centralizes external API entry and cross-cutting policies.
Read topic → - Applications and APIs
API Versioning
versioning lets APIs evolve without requiring every consumer to change at once.
Read topic → - Data and AI
Data Warehouse
a data warehouse separates analytical workloads from operational transaction systems.
Read topic → - Data and AI
Data Lake
a data lake keeps diverse data at scale before every future analytical structure is known.
Read topic → - Data and AI
ETL / ELT
ETL/ELT turns heterogeneous source data into usable analytical data.
Read topic → - Data and AI
Stream Processing
stream processing computes over continuously arriving data rather than waiting for batches.
Read topic → - Data and AI
Change Data Capture
CDC turns database changes into a consumable stream of change information.
Read topic → - Data and AI
Full-Text Search
full-text search retrieves text by linguistic content rather than exact field equality.
Read topic → - Data and AI
Embeddings / Vector Search
vector search retrieves information by semantic similarity rather than only matching words.
Read topic → - Data and AI
Hybrid Search
hybrid search combines exact textual relevance with semantic similarity.
Read topic → - Data and AI
RAG
RAG lets a model reason over external knowledge supplied at request time.
Read topic → - Data and AI
Structured Outputs
structured outputs make probabilistic model responses reliably consumable by software.
Read topic → - Data and AI
Tool Calling
tool calling connects model reasoning to external capabilities.
Read topic → - Data and AI
Agent
agents perform multi-step work by repeatedly deciding and acting based on intermediate results.
Read topic → - Data and AI
Context Management
context management decides what information the model should know right now.
Read topic → - Data and AI
Context Graph / Decision Trail
decision trails make organizational reasoning available, not merely organizational data.
Read topic → - Data and AI
Human-in-the-Loop
human-in-the-loop keeps consequential decisions under human control while automating surrounding work.
Read topic → - Identity and security
Agent Authorization
agents need controlled authority just like human users and applications.
Read topic → - Data and AI
AI Evals
evals make changes in probabilistic AI behaviour measurable.
Read topic → - Identity and security
SIEM
SIEM combines security telemetry so patterns across systems can be detected.
Read topic → - Identity and security
SOAR
SOAR automates repeatable actions following security detections.
Read topic → - Identity and security
XDR
XDR connects related security activity across multiple attack surfaces.
Read topic → - Identity and security
Network Segmentation
segmentation limits how far network access and compromise can spread.
Read topic → - Identity and security
SAST
SAST searches application code for security problems without executing the application.
Read topic → - Identity and security
DAST
DAST looks for vulnerabilities through the behaviour of a running application.
Read topic → - Identity and security
Software Composition Analysis
SCA finds security risk introduced through third-party software components.
Read topic → - Identity and security
SBOM
an SBOM tells you what software components an application contains.
Read topic → - Identity and security
Policy as Code
policy as code turns organizational rules into automatically evaluated controls.
Read topic → - Containers and delivery
Internal Developer Platform
a platform hides repeated infrastructure complexity behind reusable developer capabilities.
Read topic → - Containers and delivery
Self-Service Infrastructure
self-service lets users obtain standardized infrastructure without manual infrastructure-team intervention.
Read topic → - Containers and delivery
Reusable IaC Module
IaC modules turn repeated infrastructure patterns into reusable building blocks.
Read topic → - Cloud and architecture
Canonical Data Model
a canonical model reduces integration complexity by providing shared meaning between systems.
Read topic → - Cloud and architecture
Adapter
an adapter translates the interface the caller uses into the interface another component requires.
Read topic → - Cloud and architecture
Anti-Corruption Layer
an anti-corruption layer prevents another system's model from contaminating your own.
Read topic → - Cloud and architecture
Event-Driven Architecture
event-driven architecture connects systems through published facts rather than direct knowledge of every consumer.
Read topic → - Cloud and architecture
Architecture Decision Record
ADRs preserve the reasoning behind important architectural decisions.
Read topic → - Cloud and architecture
Non-Functional Requirement
functional requirements describe behaviour; quality attributes describe how well the system must provide it.
Read topic → - Cloud and architecture
Architecture Trade-Off
architecture is largely the management of competing desirable properties under constraints.
Read topic → - Cloud and architecture
C4 Model
C4 provides consistent levels of abstraction for communicating software architecture.
Read topic → - Cloud and architecture
CAP Theorem
network partitions force distributed systems to choose which guarantee matters more for affected operations.
Read topic → - Cloud and architecture
Eventual Consistency
eventual consistency accepts temporary disagreement in exchange for other distributed-system benefits.
Read topic → - Cloud and architecture
Strong Consistency
strong consistency prioritizes a coherent view of state, usually at coordination and availability/latency cost.
Read topic → - Applications and APIs
Backpressure
backpressure prevents fast producers from indefinitely overwhelming slower consumers.
Read topic → - Applications and APIs
Dead-Letter Queue
a DLQ isolates messages that normal processing cannot successfully handle.
Read topic → - Applications and APIs
At-Least-Once Delivery
at-least-once delivery prefers possible duplication over silently losing uncertain work.
Read topic → - Applications and APIs
Event Ordering
some business processes require preserving the relative order of related events.
Read topic → - Monitoring and reliability
Observability
observability is the ability to understand internal system behaviour from the information it exposes.
Read topic → - Networking
Service Discovery
service discovery separates stable service identity from changing network locations.
Read topic → - Networking
DNS Load Balancing
DNS can participate in distributing traffic by mapping one name to multiple destinations.
Read topic → - Networking
CDN
a CDN moves cacheable content closer to users.
Read topic → - Identity and security
TLS Termination
TLS termination centralizes where an incoming TLS connection ends.
Read topic → - Identity and security
Certificate Rotation
cryptographic credentials need lifecycle management, not just initial creation.
Read topic → - Identity and security
Certificate Revocation
revocation provides a way to distrust a certificate before its normal expiration.
Read topic → - Identity and security
SNI
SNI lets multiple TLS hostnames share the same server/IP infrastructure.
Read topic → - Applications and APIs
API Throttling vs Quota
throttling controls how fast resources are consumed; quotas control how much may be consumed.
Read topic → - Networking
HTTP Keep-Alive
persistent HTTP connections amortize connection setup across multiple requests.
Read topic → - Networking
HTTP/2 Multiplexing
HTTP/2 multiplexes multiple HTTP exchanges over one connection.
Read topic → - Networking
QUIC / HTTP/3
QUIC moves modern transport features above UDP and avoids several limitations of HTTP-over-TCP.
Read topic → - Applications and APIs
API Contract
an API contract establishes the communication expectations between independently changing systems.
Read topic → - Applications and APIs
Schema Validation
schema validation rejects structurally invalid data before it contaminates deeper processing.
Read topic → - Applications and APIs
Serialization
serialization converts application data into a representation that can cross process boundaries.
Read topic → - Applications and APIs
API Pagination
pagination bounds the amount of data transferred and processed per request.
Read topic → - Cloud and architecture
Stateless Service
stateless instances make requests less dependent on which particular server receives them.
Read topic → - Cloud and architecture
Sticky Session
sticky sessions preserve server-local session assumptions, at the cost of weaker distribution flexibility.
Read topic → - Identity and security
CORS
CORS controls cross-origin access by browser-based code.
Read topic → - Identity and security
CSRF Protection
CSRF protection prevents another site from abusing a user's authenticated browser session to perform unintended actions.
Read topic → - Identity and security
Content Security Policy
Content Security Policy limits what content a browser is allowed to execute or load.
Read topic → - Identity and security
Encryption at Rest
encryption in transit protects moving data; encryption at rest protects stored data.
Read topic → - Identity and security
Key Management System
encryption security depends on protecting and managing the keys, not merely running an encryption algorithm.
Read topic → - Identity and security
HSM
an HSM protects high-value cryptographic keys by performing operations without exporting the private key.
Read topic → - Identity and security
MFA
MFA reduces dependence on compromise of a single authentication factor.
Read topic → - Identity and security
Passkey
passkeys replace shared password secrets with phishing-resistant public-key authentication.
Read topic → - Identity and security
Token Expiration
short-lived credentials limit how long stolen authority remains useful.
Read topic → - Identity and security
Audit Log
audit logs preserve accountability for important actions.
Read topic → - Identity and security
Bastion / Jump Host
a bastion centralizes administrative access instead of exposing every server directly.
Read topic → - Identity and security
Network Security Group
cloud security groups provide distributed network access control around workloads.
Read topic → - Networking
DNS Caching
DNS caching reduces lookup latency and authoritative DNS load.
Read topic → - Networking
DNS TTL
DNS TTL balances caching efficiency against how quickly DNS changes propagate.
Read topic → - Networking
DNS Recursive Resolver
recursive resolvers perform DNS resolution on behalf of clients.
Read topic → - Networking
DNS Hierarchy
DNS scales naming by delegating authority through a hierarchy.
Read topic → - Storage and databases
RAID
RAID uses multiple disks to improve storage resilience and/or performance; it is not a replacement for backups.
Read topic → - Storage and databases
Database Normalization
normalization reduces unnecessary duplication and update inconsistencies in relational data.
Read topic → - Storage and databases
Denormalization
denormalization trades additional consistency work and storage for simpler or faster reads.
Read topic → - Storage and databases
Database Constraint
database constraints protect data invariants at the storage boundary itself.
Read topic → - Storage and databases
Optimistic Concurrency
optimistic concurrency uses a version check to prevent overwriting someone else's changes.
Read topic → - Storage and databases
Database Migration
migrations make database structure evolve reproducibly alongside software.
Read topic → - Applications and APIs
Eventual Retry / Poison Message Handling
resilient messaging distinguishes failures that may recover from messages that require intervention.
Read topic → - Applications and APIs
Outbox Pattern
the outbox pattern closes the consistency gap between database changes and message publication.
Read topic → - Cloud and architecture
Distributed Lock
distributed locks coordinate exclusive work across multiple processes or machines.
Read topic → - Monitoring and reliability
Graceful Shutdown
graceful shutdown lets workloads terminate without unnecessarily abandoning in-flight work.
Read topic → - Networking
Reverse DNS
normal DNS resolves names to addresses; reverse DNS provides address-to-name lookup.
Read topic → - Networking
Anycast
anycast lets multiple locations advertise the same IP address/prefix.
Read topic → - Networking
NAT Gateway
a NAT gateway provides controlled outbound Internet connectivity for private workloads.
Read topic → - Identity and security
DNSSEC
DNSSEC provides authenticity and integrity for DNS data; it does not encrypt DNS queries.
Read topic → - Applications and APIs
Queue Acknowledgement
acknowledgements let messaging systems distinguish delivery from successful consumption.
Read topic → - Applications and APIs
Consumer Group
consumer groups let multiple instances cooperate as one logical consumer.
Read topic → - Storage and databases
Database Read Replica
read replicas scale suitable read workloads by using replicated copies.
Read topic → - Storage and databases
Optimistic vs Pessimistic Concurrency
pessimistic concurrency makes competing updates wait; optimistic concurrency rejects updates based on stale versions.
Read topic → - Cloud and architecture
Autoscaling
autoscaling adjusts capacity as workload requirements change.
Read topic → - Monitoring and reliability
Liveness Probe
liveness answers should this workload be restarted? Readiness answers should it receive traffic?
Read topic → - Monitoring and reliability
Graceful Degradation
graceful degradation preserves useful functionality when optional capabilities fail.
Read topic → - Applications and APIs
Feature Toggle Kill Switch
a kill switch provides a fast operational way to disable problematic behaviour without redeployment.
Read topic → - Containers and delivery
Immutable Infrastructure
immutable infrastructure replaces infrastructure with known versions rather than accumulating unknown state.
Read topic → - Containers and delivery
Configuration Drift
configuration drift is the uncontrolled divergence between intended and actual system configuration.
Read topic → - Monitoring and reliability
Eventual Failure
resilient systems are designed around the expectation that components will eventually fail.
Read topic → - Data and AI
Apache Spark
Spark coordinates parallel data processing across machines to handle large workloads.
Read topic → - Computing fundamentals
Character Encoding, ASCII, and UTF
ASCII covers a small set of characters. Unicode identifies characters across writing systems. UTF-8 encodes them as bytes, which the reader must decode using the same rules.
Read topic → - Monitoring and reliability
Latency, Throughput, Bandwidth, and Percentiles
performance needs separate measurements for delay, completed work, capacity, and the experience of slower requests.
Read topic → - Computing fundamentals
CPU-Bound vs I/O-Bound Work
improve the resource that limits progress; more processing power cannot remove every kind of waiting.
Read topic → - Computing fundamentals
Concurrency, Parallelism, and Async
concurrency overlaps tasks, parallelism executes work simultaneously, and await can pause a method without blocking its thread while it waits.
Read topic → - Computing fundamentals
Race Conditions, Locks, and Deadlocks
shared mutable state needs coordination that protects the whole operation and reaches every participant.
Read topic → - Computing fundamentals
Memory Management and Resource Exhaustion
stack frames follow active function calls; heap objects have separately managed lifetimes. Keep ownership clear, bound growth, and release resources when finished.
Read topic → - Storage and databases
Storage I/O and Durability
storage performance depends on the access pattern; durability depends on what a successful write actually guarantees.
Read topic → - Monitoring and reliability
Queueing and Capacity
queues turn temporary excess demand into waiting; sustained excess demand needs more capacity or less incoming work.
Read topic → - Monitoring and reliability
Systematic Troubleshooting
troubleshooting narrows possible causes through observations and tests, then verifies that the chosen fix addresses the problem.
Read topic → - Containers and delivery
Testing Fundamentals
different tests answer different questions. Confidence comes from useful coverage of behavior, interactions, load, and failure.
Read topic → - Identity and security
Threat Modeling and Trust Boundaries
threat modeling connects valuable assets, possible harm, and system weaknesses so that protections address specific risks.
Read topic → - Monitoring and reliability
Failure Domains and Reliability Calculations
reliability depends on which failures are shared, which dependencies are required, and whether recovery works under real load.
Read topic → - Cloud and architecture
Control Plane and Data Plane
distinguish the machinery that decides and configures behavior from the machinery that performs the system's ongoing work.
Read topic → - Computing fundamentals
Algorithmic Complexity and Data Structures
O(n) grows with the list, O(log n) grows through repeated halvings, expected O(1) stays roughly constant on average, and O(n²) grows with the number of pairs.
Read topic → - Computing fundamentals
Hexadecimal
hexadecimal is a readable way to write numeric and byte values. Two hex digits represent one byte; the surrounding format determines what those bytes mean.
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