A Checkbox question type is useful when you want participants to agree to or confirm something. 

You can use Checkboxes in the body of an interaction AND in the Registration questions. If you want it in the body of an interaction, click on the “Add Question” button from the Edit Tab. If you want it in the registration form, go to the "Registration" tab and click on the “Add Field” button. In either case, you will see this window appear: 

Click on “Create Field” and your question will be created. 

Note: If you set the checkbox to be checked by default, the participant can always un-check the box before continuing. If you make the checkbox required, the participant will have to