AWS IAM Explained: How Users, Groups, Roles and Policies Control Access

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AWS Identity and Access Management (IAM) is a core AWS service that controls who can access cloud resources and what actions they are permitted to perform. IAM addresses two fundamental questions: authentication (verifying identity) and authorization (defining allowed actions). The service organizes access through four key building blocks — Users, Groups, Roles, and Policies — each serving a distinct purpose in managing permissions. Groups simplify administration by letting teams bundle permissions together, so developers or database admins inherit the right access without individual configuration. Policies are JSON-based rules that explicitly allow or deny specific actions on AWS resources, forming the foundation of the entire permission system.

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