AWS — IAM Overview

What is AWS Identity and Access Management (IAM)? — Introduction to AWS IAM.

Awesome Cloud — AWS — IAM

TL;DR:

AWS Identity and Access Management (IAM) provides fine-grained access control across AWS accounts. With IAM, you can specify who can access which services and resources, and under which conditions. IAM is a pillar of security and provides you with easy ways to secure AWS accounts and resources.