# Tag
<a name="API_Tag"></a>

Metadata that you assign to your Amazon resources. Tags enable you to categorize your resources in different ways, for example, by purpose, owner, or environment. In Amazon Systems Manager, you can apply tags to Systems Manager documents (SSM documents), managed nodes, maintenance windows, parameters, patch baselines, OpsItems, and OpsMetadata.

## Contents
<a name="API_Tag_Contents"></a>

 ** Key **   <a name="systemsmanager-Type-Tag-Key"></a>
The name of the tag.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 128.  
Pattern: `^([\p{L}\p{Z}\p{N}_.:/=+\-@]*)$`   
Required: Yes

 ** Value **   <a name="systemsmanager-Type-Tag-Value"></a>
The value of the tag.  
Type: String  
Length Constraints: Minimum length of 0. Maximum length of 256.  
Pattern: `^([\p{L}\p{Z}\p{N}_.:/=+\-@]*)$`   
Required: Yes

## See Also
<a name="API_Tag_SeeAlso"></a>

For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon SDK for C\$1\$1](https://docs.amazonaws.cn/goto/SdkForCpp/ssm-2014-11-06/Tag) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/ssm-2014-11-06/Tag) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/ssm-2014-11-06/Tag)