Radio button fields present a user with a choice that can be made by clicking on a button. Radio buttons are displayed in a set, one of which is selected by default. Selecting a new button cancels the currently selected radio button; only one radio button in a set can be selected at a time.
For example, in a survey form, a set of radio buttons could represent age ranges, and users could be prompted to click the button that corresponds to their age range.
When you set the properties of a radio button field, you assign it a group name, a value, and an initial state: selected or not selected. All radio buttons in a group must share the group name. When a form containing a set of radio buttons is submitted by a user, the group name and the value of the selected button is sent to the form handler.