AWS IAM Explained Simply: Users, Roles, Policies, and Permissions
A beginner-friendly guide to AWS Identity and Access Management, covering IAM users, roles, policies, permissions, and the principle of least privilege with simple examples.
When you start using AWS, one of the first security services you should understand is AWS Identity and Access Management, commonly known as IAM.
IAM helps you control who can access your AWS resources and what actions they are allowed to perform.
Instead of giving everyone full access to your AWS account, IAM lets you create specific permissions for different users, applications, and AWS services.
This makes your cloud environment more secure and easier to manage.
IAM Users
IAM Users
An IAM user represents a person or application that needs access to AWS.
For example, imagine a small development team with three members:
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Developer
Tester
AdministratorEach person may require different access.
The developer may need access to EC2.
The tester may only need access to logs.
The administrator may need broader management permissions.
Instead of sharing one AWS account login, IAM allows each person to have their own identity and permissions.
IAM Groups
IAM Groups
An IAM group is a collection of IAM users.
Groups make permission management easier when several users need similar access.
For example:
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Developers Group
├── User 1
├── User 2
└── User 3Instead of assigning the same permissions to each developer individually, you can attach the required policy to the Developers Group.
All users inside the group can then receive those permissions.
IAM Policies
An IAM policy is a document that defines permissions.
A policy describes which actions are allowed or denied.
For example, a policy could allow someone to:
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View EC2 instances
Start EC2 instances
Stop EC2 instanceswhile preventing them from:
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Delete EC2 instances
Modify IAM users
Access billing settingsPolicies help you precisely control what users and services can do inside AWS.
IAM Users vs IAM Roles
A simple way to remember the difference is:
| IAM User | IAM Role |
|---|---|
| Represents a specific identity | Provides temporary permissions |
| Can have long-term credentials | Commonly uses temporary credentials |
| Often associated with users or specific workloads | Frequently used by AWS services and applications |
Both are used to control access, but they serve different purposes.
Principle of Least Privilege
One of the most important security concepts in AWS is the principle of least privilege.
It means:
Give users and applications only the permissions they actually need.
For example, if a developer only needs to view EC2 instances, there is no reason to give that developer permission to delete databases or modify IAM settings.
Instead of:
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Full AWS Accessprefer:
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Only the required permissionsReducing unnecessary permissions can help limit the impact of mistakes or compromised credentials.
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