MD5 (Message-Digest Algorithm 5) is a widely used cryptographic hash function that is used to produce a unique and fixed-length digital fingerprint of a message or data. This algorithm takes in any input, regardless of its size, and produces a 128-bit hash value that is used for data integrity and authentication purposes. MD5 is known for its fast computation speed and is commonly used in digital signatures, password hashing, and file integrity checks. However, due to its vulnerability to collisions, it is no longer considered a secure option for cryptographic purposes.