# Dimension
<a name="API_Dimension"></a>

A dimension is a name/value pair that is part of the identity of a metric. Because dimensions are part of the unique identifier for a metric, whenever you add a unique name/value pair to one of your metrics, you are creating a new variation of that metric. For example, many Amazon EC2 metrics publish `InstanceId` as a dimension name, and the actual instance ID as the value for that dimension.

You can assign up to 30 dimensions to a metric.

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

 ** Name **   <a name="applicationsignals-Type-Dimension-Name"></a>
The name of the dimension. Dimension names must contain only ASCII characters, must include at least one non-whitespace character, and cannot start with a colon (`:`). ASCII control characters are not supported as part of dimension names.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 255.  
Required: Yes

 ** Value **   <a name="applicationsignals-Type-Dimension-Value"></a>
The value of the dimension. Dimension values must contain only ASCII characters and must include at least one non-whitespace character. ASCII control characters are not supported as part of dimension values.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 1024.  
Required: Yes

## See Also
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For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/application-signals-2024-04-15/Dimension) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/application-signals-2024-04-15/Dimension) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/application-signals-2024-04-15/Dimension)