Display a banner when an action is performed:

• If you want to display a success/failure banner based on whether the action performed inside the form was successful or a failure, you can use the banner response type.
• In the example here, we click the Add deal button and when the deal is created successfully, we display a success banner for the same

Edit a section inside your form:

• Say, you have 4 sections in your form and you want to edit one or all of them and display a success/failure banner displayed once the editing is successfully done, you can use sections_edit. It contains a list of the existing sections inside the form that have to be edited/modified. 
• Here, the Add deal button is clicked and a form appears, a deal is created successfully using sections_edit and a success/failure banner will be displayed.

Throw an error message when there are incorrect inputs:

• Whenever a form is submitted with unintended inputs, the form's error object allows you to throw an error message.
• Form error messages can be handled either for the entire form or for individual fields as well. 
• So, here in the example, we display an error message when the user has missed filling out a mandatory field - the email field in the form.
  

Modify fields inside your form:

• To remove, clear, update, add_before, add_after, enable or disable fields in the form, you can use form_modification.
• This response type is the output of the Form Controller's Change handler
• Here, when the email subscription box is checked, we display the checkbox section that allows users to choose the type of mails that they want to receive using form_modification.