What is Hash?
A fixed-length fingerprint of arbitrary data. Bitcoin uses SHA-256: the same input always gives the same output, and any change gives a completely different one.
A cryptographic hash is one-way: you cannot recover the input from the output, and you cannot practically find two inputs producing the same output. Bitcoin uses hashes everywhere — linking blocks, committing to transaction sets, deriving addresses.
Mining is a search for an input whose hash falls below a target. Since the output is effectively random, the only strategy is to try again with a different nonce.
Related terms
Proof of work
The mechanism that secures Bitcoin: miners must find a hash below a difficulty target, which is expensive to…
Como funcionaMerkle root
A single hash in the block header that commits to every transaction in the block, built by hashing…
MiningNonce
A 32-bit field in the block header that miners vary to change the header's hash while searching for a valid…
This definition is part of the Bitcoin Logical glossary. For the fuller explanation, start with Aprender, or see the live numbers on O Sinal Bitcoin.