Managing who can access what, and under what conditions — the NIST definition.
What it means
Per NIST, identity and access management (IAM) "broadly refers to the administration of individual identities within a system... In enterprise IT, identity management is about establishing and managing the roles and access privileges of individual network users."
IAM is foundational to security and compliance: it covers how users prove who they are (authentication) and what they're allowed to do (authorization). It appears across cloud, security, and systems-administration roles.
Definitional only.