What is IAM - Amazon Identity and Access Management
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What is IAM

Amazon Identity and Access Management (IAM) is a web service that helps you securely control access to Amazon resources. With IAM, you can manage permissions that control which Amazon resources users can access. You use IAM to control who is authenticated (signed in) and authorized (has permissions) to use resources. IAM provides the infrastructure necessary to control authentication and authorization for your Amazon Web Services accounts.

When you create an Amazon Web Services account, you begin with one sign-in identity that has complete access to all Amazon Web Services and resources in the account. This identity is called the Amazon Web Services account root user and is accessed by signing in with the email address and password that you used to create the account. We strongly recommend that you don't use the root user for your everyday tasks. Safeguard your root user credentials and use them to perform the tasks that only the root user can perform. For the complete list of tasks that require you to sign in as the root user, see Tasks that require root user credentials in the IAM User Guide. Use IAM to set up users in addition to your root user, such as administrators, analysts, and developers. and grant them access to the resources they need to succeed in their tasks.

After a user is set up in IAM, they use their sign-in credentials to authenticate with Amazon. Authentication is provided by matching the sign-in credentials to a principal (an IAM user, federated user, IAM role, or application) trusted by the Amazon Web Services account. Next, a request is made to grant the principal access to resources. Access is granted in response to an authorization request if the user has been given permission to the resource. For example, when you first sign in to the console and are on the console Home page, you aren't accessing a specific service. When you select a service, the request for authorization is sent to that service and it looks to see if your identity is on the list of authorized users, what policies are being enforced to control the level of access granted, and any other policies that might be in effect. Authorization requests can be made by principals within your Amazon Web Services account or from another Amazon Web Services account that you trust.

Once authorized, the principal can take action or perform operations on resources in your Amazon Web Services account. For example, the principal could launch a new Amazon Elastic Compute Cloud instance, modify IAM group membership, or delete Amazon Simple Storage Service buckets.

IAM, like many other Amazon services, is eventually consistent. IAM achieves high availability by replicating data across multiple servers within Amazon's data centers around the world. If a request to change some data is successful, the change is committed and safely stored. However, the change must be replicated across IAM, which can take some time. Such changes include creating or updating users, groups, roles, or policies. We recommend that you do not include such IAM changes in the critical, high-availability code paths of your application. Instead, make IAM changes in a separate initialization or setup routine that you run less frequently. Also, be sure to verify that the changes have been propagated before production workflows depend on them. For more information, see Changes that I make are not always immediately visible.

Amazon Identity and Access Management (IAM) and Amazon Security Token Service (Amazon STS) are features of your Amazon account offered at no additional charge. You are charged only when you access other Amazon services using your IAM users or Amazon STS temporary security credentials. For information about the pricing of other Amazon products, see the Amazon Web Services pricing page.

IAM is integrated with many Amazon services. For a list of Amazon services that work with IAM, see Amazon services that work with IAM.

Amazon Training and Certification provides a 10-minute video introduction to IAM:

Introduction to Amazon Identity and Access Management

For more information about IAM concepts, see the following topics: