Core IAM Components - Users, Groups, Roles, Policies

IAM is built around four core components:

1. Users

An IAM User represents a person or application with long-term credentials.

Production insight: You should avoid long-term credentials for applications. Use roles instead.

2. Groups

Groups are collections of users.

Architecturally, groups simplify permission management:

  • Attach policy to group.
  • Add users to group.
  • Permissions scale automatically.

3. Roles

A Role is an identity with temporary credentials.

Roles are assumed by:

AWS services (EC2, Lambda)

  • Applications
  • External accounts
  • Roles are fundamental to secure architecture because they eliminate static credentials.

Example: An EC2 instance assumes a role that allows access to S3. No hardcoded keys.

4. Policies

Policies define permissions.

They answer:

  • What actions?
  • On what resources?
  • Under which conditions?

Policies are JSON documents evaluated by AWS.

Production insight: Always prefer:

  • Least privilege
  • Role-based access
  • Avoid wildcard permissions (*) unless justified

In this section, I learned:

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