How are hidden fields used in Forms?

The "Hidden Fields" section of the Form builder allows you to include additional field data and category information to be submitted that the subscriber does not see.

Examples could include:

1. Use Source to track which subscribe form was used to acquire a contact.
2. Select a SMS keyword to add the contact to when a SMS Phone Number is collected in the form. To use this feature, your SMS Keyword must be configured for the double opt-in process.
3. Use a Date field to pass the current date into the selected field on subscriber records.
4. Use a Text or Numeric field to pass a specific value into the selected field on subscriber records. For example, pass the value "Prospect" into the Text1 field. 
5. Choose categories to add the subscriber to that are not visible to the subscriber.