# Use the Classification Service

> To classify a document, add the `projectId`, the `documentId` received in the previous step, and the `classifierId`. To discover classifiers, call the Discover Classifiers routes or the Get Project By Id endpoint. [Here](https://docs.uipath.com/document-understanding/automation-suite/2024.10/api-guide/use-the-discovery-service) are more details about how to use the Discovery Service for retrieving information about the project's available classifiers and extractors. The response body provides information about the uploaded document.

To classify a document, add the `projectId`, the `documentId` received in the previous step, and the `classifierId`. To discover classifiers, call the Discover Classifiers routes or the Get Project By Id endpoint. [Here](https://docs.uipath.com/document-understanding/automation-suite/2024.10/api-guide/use-the-discovery-service) are more details about how to use the Discovery Service for retrieving information about the project's available classifiers and extractors. The response body provides information about the uploaded document.

The POST call for Classification can be done for synchronous or asynchronous consumption.

:::note
Classification data is soft deleted after one day.
:::

The following examples are using a POST call for synchronous consumption.

Depending on the operation, Document Understanding API calls use the following classes:

* [Document Class](https://docs.uipath.com/activities/other/latest/document-understanding/document-class) for digitized documents.
* [Classification Result](https://docs.uipath.com/activities/other/latest/document-understanding/classification-result-class) for classification results.