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

A tag object that consists of a key and an optional value, used to manage metadata for SageMaker Amazon resources.

You can add tags to notebook instances, training jobs, hyperparameter tuning jobs, batch transform jobs, models, labeling jobs, work teams, endpoint configurations, and endpoints. For more information on adding tags to SageMaker resources, see [AddTags](https://docs.amazonaws.cn/sagemaker/latest/APIReference/API_AddTags.html).

For more information on adding metadata to your Amazon resources with tagging, see [Tagging Amazon resources](https://docs.amazonaws.cn/general/latest/gr/aws_tagging.html). For advice on best practices for managing Amazon resources with tagging, see [Tagging Best Practices: Implement an Effective Amazon Resource Tagging Strategy](https://d1.awsstatic.com/whitepapers/aws-tagging-best-practices.pdf).

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

 ** Key **   <a name="sagemaker-Type-Tag-Key"></a>
The tag key. Tag keys must be unique per resource.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 128.  
Pattern: `([\p{L}\p{Z}\p{N}_.:/=+\-@]*)`   
Required: Yes

 ** Value **   <a name="sagemaker-Type-Tag-Value"></a>
The tag value.  
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/sagemaker-2017-07-24/Tag) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/sagemaker-2017-07-24/Tag) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/sagemaker-2017-07-24/Tag)