# Classifier


Classifiers are triggered during a crawl task. A classifier checks whether a given file is in a format it can handle. If it is, the classifier creates a schema in the form of a `StructType` object that matches that data format.

You can use the standard classifiers that AWS Glue provides, or you can write your own classifiers to best categorize your data sources and specify the appropriate schemas to use for them. A classifier can be a `grok` classifier, an `XML` classifier, a `JSON` classifier, or a custom `CSV` classifier, as specified in one of the fields in the `Classifier` object.

## Contents


 ** CsvClassifier **   <a name="Glue-Type-Classifier-CsvClassifier"></a>
A classifier for comma-separated values (CSV).  
Type: [CsvClassifier](API_CsvClassifier.md) object  
Required: No

 ** GrokClassifier **   <a name="Glue-Type-Classifier-GrokClassifier"></a>
A classifier that uses `grok`.  
Type: [GrokClassifier](API_GrokClassifier.md) object  
Required: No

 ** JsonClassifier **   <a name="Glue-Type-Classifier-JsonClassifier"></a>
A classifier for JSON content.  
Type: [JsonClassifier](API_JsonClassifier.md) object  
Required: No

 ** XMLClassifier **   <a name="Glue-Type-Classifier-XMLClassifier"></a>
A classifier for XML content.  
Type: [XMLClassifier](API_XMLClassifier.md) object  
Required: No

## See Also


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/glue-2017-03-31/Classifier) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/glue-2017-03-31/Classifier) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/glue-2017-03-31/Classifier)