# Tagging AWS Organizations resources
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A *tag* is a custom attribute label that you add to an AWS resource to 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 can be up to 128 characters in length and are case sensitive.
+ A *tag value* (for example, `111122223333` or `Production`). Tag values can be up to 256 characters in length, and like tag keys, are case sensitive. You can set the value of a tag to an empty string, but you can't set the value of a tag to null. Omitting the tag value is the same as using an empty string. 

For more information about what characters are allowed in a tag key or value, see the [Tags parameter of the Tag API](https://docs.aws.amazon.com/ARG/latest/APIReference/API_Tag.html#ARG-Tag-request-Tags) in the *Resource Groups Tagging API Reference*.

You can use tags to categorize resources by purpose, owner, environment, or other criteria. For more information, see [Best Practices for Tagging AWS Resources](https://docs.aws.amazon.com/whitepapers/latest/tagging-best-practices/tagging-best-practices.html).

**Tip**  
Use [tag policies](orgs_manage_policies_tag-policies.md) to help standardize your implementation of tags across the resources in your organization's accounts.

**Topics**
+ [Considerations](#orgs_tagging_considerations)
+ [Using tags](use-tags.md)
+ [Adding, updating, and removing tags](add-tag.md)

## Considerations
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AWS Organizations supports the following tagging operations when you are logged in to the management account:

**You can add tags to the following organization resources**
+ AWS accounts
+ Organizational units
+ The organization's root
+ Policies

**You can add tags at the following times**
+ [When you create the resource](add-tag.md#add-tag-new) — Specify the tags in either the Organizations console, or use the `Tags` parameter with one of the `Create` API operations. This isn't applicable to the organization's root. 
+ [After you create the resource](add-tag.md#add-tag-existing) — Use the Organizations console, or call the `[TagResource](https://docs.aws.amazon.com/organizations/latest/APIReference/API_TagResource.html)` operation.

**Other considerations**

You can view the tags on any of the taggable resources in AWS Organizations by using the console or by calling the `[ListTagsForResource](https://docs.aws.amazon.com/organizations/latest/APIReference/API_ListTagsForResource.html)` operation.

You can remove tags from a resource by specifying the keys to remove by using the console or by calling the `[UntagResource](https://docs.aws.amazon.com/organizations/latest/APIReference/API_UntagResource.html)` operation.