A radio button or option button[1] is a graphical control element that allows the user to choose only one of a predefined set of mutually exclusive options.
[2] The singular property of a radio button makes it distinct from checkboxes, where the user can select and unselect any number of items.
Radio buttons are arranged in groups of two or more and displayed on screen as, for example, a list of circular holes that can contain white space (for unselected) or a dot (for selected).
Version 6 of the Unicode standard includes a character designated to represent a radio button, (🔘) at code point 128,280 (U+1F518), found in the Miscellaneous Symbols and Pictographs section.
The font Wingdings 2 contains at position 153 and 158 glyphs that look like radio buttons.