Hash Functions
A hash function turns any input into a fixed-length string of characters that acts like a digital fingerprint.
In depth
Feed it a single letter or an entire movie and you get an output of the same length. Change even one character of the input and the output changes completely, and you cannot work backwards from the fingerprint to the original data. These properties make hashes perfect for detecting tampering.
Why it matters
Hashes link blocks together, identify transactions and power mining — they are everywhere in a blockchain.