Any of a number of special characters that exist in most coded character sets and that are input or output to cause some special action rather than as part of the normal textual data.Control characters are input by holding down a control key on the keyboard and simultaneously pressing a letter key or (depending on the keyboard and operating system) certain punctuation characters. Some control codes have their own special keys: escape, tab, delete, backspace, return, allowing them to be entered with a single key press. Control characters may be output for their effect on the output device, e.g. moving the cursor or print head to the start of a new line (carriage return, Control-M), advancing down to the next line (line feed, Control-J) or ringing the bell (Control-G). Different operating systems and application programs have different conventions for what effect typing certain control characters will have, such as interrupting the current process (Unix Control-C) or suspending or resuming output (Control-S, Control-Q). See ASCII character table.
Last updated: 2015-03-07