Deployment Pipeline

Problem 

The same application must move through:
DEV → TEST → PROD
You want the same controlled process rather than three unrelated manual deployments.

Solution — Deployment Pipeline

Automate promotion through environments with checks and approvals. 
Build
  ↓
DEV
  ↓
TEST
  ↓ approval
PROD
Core idea: deployment pipelines make environment promotion repeatable and controlled.