Hashing is a process that takes some input data (like a password, a file, or even a whole text) and runs it through a hash function to produce a fixed-size output called a hash or digest.

Think of it like this:

You put any size of text into a special machine, and it gives you back a short, unique-looking “fingerprint” for that text.

How Hashing Works

1. Input – Any data (text, file, number, etc.)
2. Hash Function – A mathematical algorithm that processes the input
3. Output – A fixed-length string of characters (hash)

Example with SHA-256:

Input: "Hello"
Output: 185f8db32271fe25f561a6fc938b2e264306ec304eda518007d1764826381969

If you change just one letter:

Input: "hello"
Output: 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

The result is totally different — this is called the avalanche effect.

Key Features of Hashing

• One-way – You can’t reverse a hash to get the original data.
• Deterministic – Same input always gives the same output.
• Fixed size – Output length is always the same, no matter the input size.
• Collision-resistant – It’s hard to find two different inputs with the same output.