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

Metadata assigned to the stream or consumer, consisting of a key-value pair.

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

 ** Key **   <a name="Streams-Type-Tag-Key"></a>
A unique identifier for the tag. Maximum length: 128 characters. Valid characters: Unicode letters, digits, white space, \_ . / = \+ - % @  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 128.  
Required: Yes

 ** Value **   <a name="Streams-Type-Tag-Value"></a>
An optional string, typically used to describe or define the tag. Maximum length: 256 characters. Valid characters: Unicode letters, digits, white space, \_ . / = \+ - % @  
Type: String  
Length Constraints: Minimum length of 0. Maximum length of 256.  
Required: No

## 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\+\+](https://docs.amazonaws.cn/goto/SdkForCpp/kinesis-2013-12-02/Tag) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/kinesis-2013-12-02/Tag) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/kinesis-2013-12-02/Tag)