An Amazon Resource Name (ARN) is a string that uniquely identifies an AWS resource, such as EC2 instances, S3 buckets, accounts, Lambda functions, and more. AWS requires an ARN when you want to specify a resource unambiguously across all of AWS, such as in IAM policies, Amazon Relational Database Service (Amazon RDS) tags, and API calls. ARNs are constructed from identifiers that specify the service, Region, account, and other information. There are three ARN formats:

• arn:aws:service:region:account-id:resource-id
• arn:aws:service:region:account-id:resource-type/resource-id
• arn:aws:service:region:account-id:resource-type:resource-id

The exact format of an ARN depends on the service and resource type. To learn more about ARNs, see Amazon Resource Names (ARNs) and AWS Service Namespaces and ARN Formats. To look up the ARN format for a specific AWS resource, open the Service Authorization Reference, open the page for the service, and navigate to the resource types table. Finding the ARN of an AWS object can be done in several ways, including using the AWS service console, constructing the ARN yourself by following the appropriate format, or using the AWS CLI.