If you make a field required, the user cannot submit your form without filling out that field.
Make a field required by either clicking on the asterisk next to the label in the form builder or clicking the checkbox in the field editor on the left side of the builder.
Required fields that are not filled out will be highlighted in red when the user hits the submit button.
If a field has been marked as required and has multiple parts to fill out (such as Address or Name fields), then each field must have a value to allow the viewer to submit it. One exception to this is Address Line 2, which can be left blank even if an Address Field is marked as being required. Below you can see what happens when a required Name field is missing the middle initial and required Address field is missing the City:
Once corrected, the red highlighting will go away and the Form can be submitted:
If you've selected the field option for 'Add Other' on Radio Button or Checkbox fields, then the field that appears under the Other option must be filled in if the field is marked as required. If that option is selected on a required field and no value is placed within the field, an error will be given indicating the field needs a value when the submission is attempted.
Once a value has been placed in the 'Other' field, then the highlighting/error will go away and the Form can be submitted.
If you have a multi-page form, you can turn on Skip Validation in Form Extras to allow your users to navigate between pages without worrying about filling in every required field. Each required field must be complete before submitting the form.