# Tag


Metadata assigned to an Amazon RDS resource consisting of a key-value pair.

For more information, see [Tagging Amazon RDS resources](https://docs.amazonaws.cn/AmazonRDS/latest/UserGuide/USER_Tagging.html) in the *Amazon RDS User Guide* or [Tagging Amazon Aurora and Amazon RDS resources](https://docs.amazonaws.cn/AmazonRDS/latest/AuroraUserGuide/USER_Tagging.html) in the *Amazon Aurora User Guide*. 

## Contents


**Note**  
In the following list, the required parameters are described first.

 ** Key **   
A key is the required name of the tag. The string value can be from 1 to 128 Unicode characters in length and can't be prefixed with `aws:` or `rds:`. The string can only contain only the set of Unicode letters, digits, white-space, '\$1', '.', ':', '/', '=', '\$1', '-', '@' (Java regex: "^([\$1\$1p\$1L\$1\$1\$1p\$1Z\$1\$1\$1p\$1N\$1\$1.:/=\$1\$1\$1-@]\$1)\$1").  
Type: String  
Required: No

 ** Value **   
A value is the optional value of the tag. The string value can be from 1 to 256 Unicode characters in length and can't be prefixed with `aws:` or `rds:`. The string can only contain only the set of Unicode letters, digits, white-space, '\$1', '.', ':', '/', '=', '\$1', '-', '@' (Java regex: "^([\$1\$1p\$1L\$1\$1\$1p\$1Z\$1\$1\$1p\$1N\$1\$1.:/=\$1\$1\$1-@]\$1)\$1").  
Type: String  
Required: No

## See Also


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/rds-2014-10-31/Tag) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/rds-2014-10-31/Tag) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/rds-2014-10-31/Tag)