MD5 uses the Merkle–Damgård construction with a 512-bit block size. Each block goes through 64 rounds of operations involving bitwise logical functions (AND, OR, XOR, NOT), modular additions, and left rotations. The design prioritized security against cryptanalysis — albeit with the computational limits of 1991.

Extremely stable and widely used in big data (Presto, RocksDB, etc.).