AWS General Reference
Reference guide (Version 1.0)

Tagging AWS Resources

Tags are custom attributes to your AWS resources that make it easier to identify, organize, and search for resources. Each tag has two parts:

  • A tag key (for example, CostCenter, Environment, or Project). Tag keys are case sensitive.

  • An optional field known as a tag value (for example, 111122223333 or Production). Omitting the tag value is the same as using an empty string. Like tag keys, tag values are case sensitive.

You can use tags to categorize resources by purpose, owner, environment, or other criteria. For more information, see AWS Tagging Strategies.

You can add, change, or remove tags one resource at a time from each resource’s service console, service API, or the AWS CLI.

Tag Naming and Usage Conventions

The following basic naming and usage conventions apply to tags:

  • Each resource can have a maximum of 50 tags.

  • For each resource, each tag key must be unique, and each tag key can have only one value.

  • The maximum tag key length is 128 Unicode characters in UTF-8.

  • The maximum tag value length is 256 Unicode characters in UTF-8.

  • Allowed characters can vary by AWS service. For information about what characters you can use to tag resources in a particular AWS service, see its documentation. In general, allowed characters in tags are letters, numbers, spaces representable in UTF-8, and the following characters: . : + = @ _ / - (hyphen).

  • Tag keys and values are case sensitive. As a best practice, decide on a strategy for capitalizing tags, and consistently implement that strategy across all resource types. For example, decide whether to use Costcenter, costcenter, or CostCenter, and use the same convention for all tags. Avoid using similar tags with inconsistent case treatment.

  • The aws: prefix is reserved for AWS use. You can't edit or delete a tag's key or value when the tag has a tag key with the aws: prefix. Tags with a tag key with the aws: prefix do not count against your tags per resource limit.

More Information on Tagging

This page provides general information on tagging AWS resources. For more information about tagging resources in a particular AWS service, see its documentation. The following are also good sources of information about tagging: