Password Hashing

Problem

Your application needs to verify passwords. 
If you store:
alice → MySecretPassword123
a database leak immediately reveals everyone's passwords.

Solution — Password Hashing

Store a salted, deliberately expensive password-derived hash instead. 
password + salt
       ↓
password hashing function
       ↓
stored value
At login, hash the submitted password appropriately and compare.
Core idea: servers should verify passwords without storing the original passwords.