This tutorial assumes you've followed the tutorials described in the **Create and share an app** sequence of tutorials, up through **Defining classes**.

Fields are the pieces of text that an AI Hub app extracts from documents. Each document class has its own defined fields. In this guide you'll learn how to define fields for a class.

Let's add a new field to the **Bank Statement** class

Make sure you're viewing a document in the **Bank Statement** class, so the **Bank Statement** class definition (or "schema") is open in the right pane

Click **Add field**

For simple extractions, all you need to do is give the field a name

Click the **Enter field name** field and type [[Customer Name]]

Click the **X** to close the field definition

Let's add another field. Click **Add field** again

Click the **Enter field name** field and type [[Customer Address]]

Let's add a third field. Click **Add field**

Click the **Enter field name** field and type [[Bank]]

This field will contain the name of the bank

Now that the class has some fields defined, the project extracts text from the document selected in the left pane and populates the fields in the right pane

Click the **Customer Address** field in the right pane to see a blue box around the portion of the document that the app extracted that field's data from

Switch to another document in the same class by clicking the document in the left pane

The project populates the fields on the right with data from the new document, even though it has a different layout than the first document

Define fields