# Introduction to IAM concepts
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Amazon Identity and Access Management (IAM) is an Amazon service that helps an administrator to more securely control access to Amazon resources. Administrators control who can be *authenticated* (signed in) and *authorized* (have permissions) to use Amazon Quick resources. IAM is an Amazon service that you can use with no additional charge.

IAM is used with Amazon Quick in several ways, including the following:
+ If your company uses IAM for their identity management, people might have IAM user names and passwords that they use to sign in to Amazon Quick.
+ If you want your Amazon Quick users to be automatically created at first sign-in, you can use IAM to create a policy for users who are preauthorized to use Amazon Quick.
+ If you want to create specialized access for specific groups of Amazon Quick users or to specific resources, you can use IAM policies to accomplish this.

**Topics**
+ [Audience](#security_iam_audience)
+ [Authenticating with identities](#security_iam_authentication)
+ [Managing access using policies](#security_iam_access-manage)

## Audience
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Use the following to help understand the context of the information provided in this section, and how it applies to your role. How you use Amazon Identity and Access Management (IAM) differs depending on the work that you do in Amazon Quick.

**Service user** – In some cases, you might use Amazon Quick as an Author or Reader to interact with data, analyses, and dashboards, spaces, and agents through the Amazon Quick by using the browser interface. In these cases, this section provides only background information for you. You don't directly interact with the IAM service, except if you use IAM to sign into Amazon Quick.

**Amazon Quick administrator** – If you're in charge of Amazon Quick resources at your company, you probably have full access to Amazon Quick. It's your job to determine which Amazon Quick features and resources your team members should access. If you have specialized requirements that you can't solve by using the Amazon Quick admin panel, then you can work with your administrator to create permissions policies for your Amazon Quick users. To learn more about IAM, read this page to understand the basic concepts of IAM. To learn more about how your company can use IAM with Amazon Quick, see [Using Amazon Quick with IAM](https://docs.amazonaws.cn/quicksight/latest/user/security_iam_service-with-iam.html).

**Administrator** – If you're a system administrator, you might want to learn details about how you can write policies to manage access to Amazon Quick. To view examples of Amazon Quick identity-based policies that you can use in IAM, see [IAM identity-based policies for Amazon Quick](https://docs.amazonaws.cn/quicksight/latest/user/iam-policy-examples.html#security_iam_id-based-policy-examples).

## Authenticating with identities
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Authentication is how you sign in to Amazon using your identity credentials. You must be authenticated as the Amazon Web Services account root user, an IAM user, or by assuming an IAM role.

For programmatic access, Amazon provides an SDK and CLI to cryptographically sign requests. For more information, see [Amazon Signature Version 4 for API requests](https://docs.amazonaws.cn/IAM/latest/UserGuide/reference_sigv.html) in the *IAM User Guide*.

**Topics**
+ [Amazon Web Services account root user](#security_iam_authentication-rootuser)
+ [IAM users and groups](#security_iam_authentication-iamuser)
+ [IAM roles](#security_iam_authentication-iamrole)

### Amazon Web Services account root user
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 When you create an Amazon Web Services account, you begin with one sign-in identity called the Amazon Web Services account *root user* that has complete access to all Amazon Web Services services and resources. We strongly recommend that you don't use the root user for everyday tasks. For tasks that require root user credentials, see [Tasks that require root user credentials](https://docs.amazonaws.cn/IAM/latest/UserGuide/id_root-user.html#root-user-tasks) in the *IAM User Guide*. 

### IAM users and groups
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An *[IAM user](https://docs.amazonaws.cn/IAM/latest/UserGuide/id_users.html)* is an identity with specific permissions for a single person or application. We recommend using temporary credentials instead of IAM users with long-term credentials. For more information, see [Require human users to use federation with an identity provider to access Amazon using temporary credentials](https://docs.amazonaws.cn/IAM/latest/UserGuide/best-practices.html#bp-users-federation-idp) in the *IAM User Guide*.

An [https://docs.amazonaws.cn/IAM/latest/UserGuide/id_groups.html](https://docs.amazonaws.cn/IAM/latest/UserGuide/id_groups.html) specifies a collection of IAM users and makes permissions easier to manage for large sets of users. For more information, see [Use cases for IAM users](https://docs.amazonaws.cn/IAM/latest/UserGuide/gs-identities-iam-users.html) in the *IAM User Guide*.

### IAM roles
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An *[IAM role](https://docs.amazonaws.cn/IAM/latest/UserGuide/id_roles.html)* is an identity with specific permissions that provides temporary credentials. You can assume a role by [switching from a user to an IAM role (console)](https://docs.amazonaws.cn/IAM/latest/UserGuide/id_roles_use_switch-role-console.html) or by calling an Amazon CLI or Amazon API operation. For more information, see [Methods to assume a role](https://docs.amazonaws.cn/IAM/latest/UserGuide/id_roles_manage-assume.html) in the *IAM User Guide*.

IAM roles are useful for federated user access, temporary IAM user permissions, cross-account access, cross-service access, and applications running on Amazon EC2. For more information, see [Cross account resource access in IAM](https://docs.amazonaws.cn/IAM/latest/UserGuide/access_policies-cross-account-resource-access.html) in the *IAM User Guide*.

## Managing access using policies
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You control access in Amazon by creating policies and attaching them to Amazon identities or resources. A policy defines permissions when associated with an identity or resource. Amazon evaluates these policies when a principal makes a request. Most policies are stored in Amazon as JSON documents. For more information about JSON policy documents, see [Overview of JSON policies](https://docs.amazonaws.cn/IAM/latest/UserGuide/access_policies.html#access_policies-json) in the *IAM User Guide*.

Using policies, administrators specify who has access to what by defining which **principal** can perform **actions** on what **resources**, and under what **conditions**.

By default, users and roles have no permissions. An IAM administrator creates IAM policies and adds them to roles, which users can then assume. IAM policies define permissions regardless of the method used to perform the operation.

### Identity-based policies
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Identity-based policies are JSON permissions policy documents that you attach to an identity (user, group, or role). These policies control what actions identities can perform, on which resources, and under what conditions. To learn how to create an identity-based policy, see [Define custom IAM permissions with customer managed policies](https://docs.amazonaws.cn/IAM/latest/UserGuide/access_policies_create.html) in the *IAM User Guide*.

Identity-based policies can be *inline policies* (embedded directly into a single identity) or *managed policies* (standalone policies attached to multiple identities). To learn how to choose between managed and inline policies, see [Choose between managed policies and inline policies](https://docs.amazonaws.cn/IAM/latest/UserGuide/access_policies-choosing-managed-or-inline.html) in the *IAM User Guide*.

### Resource-based policies
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Resource-based policies are JSON policy documents that you attach to a resource. Examples include IAM *role trust policies* and Amazon S3 *bucket policies*. In services that support resource-based policies, service administrators can use them to control access to a specific resource. You must [specify a principal](https://docs.amazonaws.cn/IAM/latest/UserGuide/reference_policies_elements_principal.html) in a resource-based policy.

Resource-based policies are inline policies that are located in that service. You can't use Amazon managed policies from IAM in a resource-based policy.

### Access control lists (ACLs)
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Access control lists (ACLs) control which principals (account members, users, or roles) have permissions to access a resource. ACLs are similar to resource-based policies, although they do not use the JSON policy document format.

Amazon S3, Amazon WAF, and Amazon VPC are examples of services that support ACLs. To learn more about ACLs, see [Access control list (ACL) overview](https://docs.amazonaws.cn/AmazonS3/latest/userguide/acl-overview.html) in the *Amazon Simple Storage Service Developer Guide*.

### Other policy types
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Amazon supports additional policy types that can set the maximum permissions granted by more common policy types:
+ **Permissions boundaries** – Set the maximum permissions that an identity-based policy can grant to an IAM entity. For more information, see [Permissions boundaries for IAM entities](https://docs.amazonaws.cn/IAM/latest/UserGuide/access_policies_boundaries.html) in the *IAM User Guide*.
+ **Service control policies (SCPs)** – Specify the maximum permissions for an organization or organizational unit in Amazon Organizations. For more information, see [Service control policies](https://docs.amazonaws.cn/organizations/latest/userguide/orgs_manage_policies_scps.html) in the *Amazon Organizations User Guide*.
+ **Resource control policies (RCPs)** – Set the maximum available permissions for resources in your accounts. For more information, see [Resource control policies (RCPs)](https://docs.amazonaws.cn/organizations/latest/userguide/orgs_manage_policies_rcps.html) in the *Amazon Organizations User Guide*.
+ **Session policies** – Advanced policies passed as a parameter when creating a temporary session for a role or federated user. For more information, see [Session policies](https://docs.amazonaws.cn/IAM/latest/UserGuide/access_policies.html#policies_session) in the *IAM User Guide*.

### Multiple policy types
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When multiple types of policies apply to a request, the resulting permissions are more complicated to understand. To learn how Amazon determines whether to allow a request when multiple policy types are involved, see [Policy evaluation logic](https://docs.amazonaws.cn/IAM/latest/UserGuide/reference_policies_evaluation-logic.html) in the *IAM User Guide*.