# Tagging your AWS FIS resources
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A *tag* is a metadata label that either you or AWS assigns to an AWS resource. Each tag consists of a *key* and a *value*. For tags that you assign, you define the key and the value. For example, you might define the key as `purpose` and the value as `test` for a resource.

Tags help you do the following:
+ Identify and organize your AWS resources. Many AWS services support tagging, so you can assign the same tag to resources from different services to indicate that the resources are related.
+ Control access to your AWS resources. For more information, see [Controlling Access Using Tags](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_tags.html) in the *IAM User Guide*.

## Tagging restrictions
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The following basic restrictions apply to tags on AWS FIS resources:
+ Maximum number of tags that you can assign to a resource: 50
+ Maximum key length: 128 Unicode characters
+ Maximum value length: 256 Unicode characters
+ Valid characters for keys and values: a-z, A-Z, 0-9, space, and the following characters: \$1 . : / = \$1 - and @
+ Keys and values are case sensitive
+ You cannot use `aws:` as a prefix for keys, because it's reserved for AWS use

## Work with tags
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The following AWS Fault Injection Service (AWS FIS) resources support tagging:
+ Actions
+ Experiments
+ Experiment templates

You can use the console to work with tags for experiments and experiment templates. For more information, see the following:
+ [Tag an experiment](tag-experiment.md)
+ [Tag experiment templates](tag-experiment-template.md)

You can use the following AWS CLI commands to work with tags for actions, experiments, and experiment templates:
+ [tag-resource](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/fis/tag-resource.html) – Add tags to a resource.
+ [untag-resource](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/fis/untag-resource.html) – Remove tags from a resource.
+ [list-tags-for-resource](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/fis/list-tags-for-resource.html) – List the tags for a specific resource.