This document discusses the Argon2id cryptographic hash function. Argon2id is designed to be memory-hard to resist password cracking attacks. It is composed of two variants, Argon2d and Argon2i. Argon2d maximizes resistance to GPU attacks by accessing memory in a password-dependent order, while Argon2i accesses memory independently of the password to resist side-channel attacks. The document describes the specification, operation, and implementation of Argon2id using the Blake2b hash function. Argon2id takes inputs like a password, salt, and parameters and iterates the Blake2b compression function over a memory array to produce the output hash.