Definition
SHA-256 (Secure Hash Algorithm 256-bit) is a member of the SHA-2 family designed by the NSA and published by NIST. It produces a 256-bit hash from any input. Bitcoin’s Proof of Work specifically uses double SHA-256: the input is hashed twice in succession (SHA-256(SHA-256(block_header))).
SHA-256 is the reason Bitcoin ASICs exist. The algorithm’s operations (bitwise logic, addition, rotation) can be implemented extremely efficiently in custom silicon, leading to the development of specialized mining chips like the BM1366, BM1370, and others.
In Simple Terms
The cryptographic algorithm Bitcoin uses for mining. ASIC chips are designed specifically to compute SHA-256 at high speed.
The cryptographic hash function used in Bitcoin mining. SHA-256 takes any input and produces a fixed 256-bit (32-byte) output. Bitcoin uses double SHA-256 for block hashing.