How to make a field Required
You can make any field "Required" in your widget, which means that your visitor has to enter the information in that field to be able to submit the form.
When editing your widget, you can check the "Required" box to make your field required.
In this example, the Email field is required but the name field isn't. Meaning, your visitors can't submit the form unless they enter their email address. However, in this example, they could leave the name field empty.