MD5 is a widely used cryptographic hash function that was created in the early 1990s by Professor Ronald L. Rivest. It stands for "Message-Digest Algorithm 5". The purpose of a hash function is to take an input (or "message") and produce a fixed-sized string of bytes that represents the input in a unique and deterministic manner. The output is often referred to as the "hash" or "digest".

Secure Hash Algorithms (SHAs) are a family of cryptographic hash functions that are widely used to ensure data integrity and security. They are used in various applications such as digital signatures, password protection, data encryption, and others.
Ref: owuk.com A hash function is a mathematical algorithm that takes an input (message) and returns a fixed-length output, known as the hash value.