SHA-256 is a cryptographic hashing algorithm that is used for generating a 256-bit hash value from any given data. This hash value can be used to verify the integrity and authenticity of data since it is almost impossible for two different inputs to generate the same hash value.

SHA-256 was designed by the US National Security Agency (NSA) in 2001 and is part of the Secure Hash Algorithm (SHA) family of algorithms. It is a one-way algorithm that takes an input of any length (up to 2^64 bits) and returns an output of 256 bits. The output of SHA-256 is a unique 32 byte (256 bit) string.

The SHA-256 algorithm is structured in such a way that it takes a given input and runs it through a series of round functions that ultimately produce a 256 bit output. This output is resilient to any kind of corruption or distortion of the input data which makes it suitable for use in verifying the integrity of data.

SHA-256 is also designed to be resistant to all known cryptanalytic attacks as well as preimage, second preimage, brute-force and collision attacks. This makes SHA-256 a secure hashing algorithm that can be used for transmission, storage and other applications where data integrity needs to be verified.