A radio button is a window with text displayed to the right of a small circular indicator. Each time the user selects a radio button, that button's state toggles between selected and unselected. This state remains until the next time the user selects the button. An application typically uses radio buttons in groups.

Within a group, usually one button is selected by default, and the user can move the selection to another button by using the cursor keys; however, only one button can be selected at a time. Radio buttons are appropriate if an exclusive choice is required from a fixed list of related options. For example, applications often use radio buttons to allow the user to select the screen foreground and background colors. A radio-button control sends WM_CONTROL messages to its owner window.