What Is IAM?

IAM (Identity and Access Management) is how AWS decides who may do what. It is the service that governs every permission in your account, and it costs nothing to use.

IAM has users (people), roles (identities that services or people temporarily assume), and policies (documents describing what is allowed).

Running aws iam list-users shows the users in your account — the starting point for understanding who has access.

A common stumble is doing everyday work as the root user. Root can do anything, including closing the account; create IAM users with only the permissions they need.

In real work, the principle of least privilege — grant only what is required — is the foundation of AWS security, and IAM is how you apply it.