Hash functions are one of those foundational computing concepts that show up everywhere — file integrity checks, password storage, digital signatures, API authentication, blockchain — but the choice of which hash to use is often made without understanding what actually differs between them.
Let me explain the practical differences clearly.
What a Hash Function Does
A hash function takes an input of any length and returns a fixed-length output (the "hash" or "digest"). The key properties:
Deterministic — the same input always produces the same output
