The 256-bit cryptographic hash function standardized by NIST in 2002 is SHA-256.
SHA-256 belongs to the SHA-2 family of cryptographic hash functions. It accepts input of arbitrary length and produces a fixed 256-bit digest, usually written as 64 hexadecimal characters. A tiny change in the input normally produces a substantially different digest, a property called the avalanche effect.
NIST published the SHA-2 family in the Federal Information Processing Standards publication FIPS PUB 180-2 in 2002. SHA-256 is used in integrity checks, digital signatures, certificate systems, and many blockchain implementations. Hashing is not encryption: encryption is designed to be reversible with a key, while a secure cryptographic hash is designed to be computationally infeasible to reverse.
SHA-256 should also be distinguished from SHA-1 and MD5, older algorithms that have serious collision weaknesses. For password storage, a fast general-purpose hash alone is not ideal; purpose-built password-hashing algorithms add salting and computational cost.