AWS Organizations is a service that enables Amazon Web Services (AWS) customers to consolidate and centrally manage multiple AWS accounts. With AWS Organizations, you can create accounts and invite existing accounts to join your organization. You can organize those accounts into groups and attach policy-based controls. If you already have a Consolidated Billing family of accounts, those accounts automatically become part of your organization.

User Guide
Introduces you to AWS Organizations, helps you set up an organization by inviting other accounts to join, and shows you how to organize your accounts into groups to control access to your AWS resources by applying service control policies.
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AWS Organizations section of AWS CLI Reference
Describes the AWS CLI commands that you can use to administer AWS Organizations. Provides syntax, options, and usage examples for each command.

API Reference
Describes all the API operations for AWS Organizations in detail. Also provides sample requests, responses, and errors for the supported web services protocols.