SHA-256

SHA-256 is a cryptographic hash function from the SHA-2 family that takes any input and produces a fixed 256-bit output, usually written as 64 hexadecimal characters. The same input always yields the same hash, while any change to the input produces a completely different one, and the function is one-way: you cannot reconstruct the input from the hash. These properties make it useful for verifying that a file has not changed, fingerprinting data, and building other security constructs. One caveat worth stating: a bare fast hash like SHA-256 is not the right way to store passwords, which need a deliberately slow, salted algorithm such as bcrypt or Argon2.