In music notation, a natural is a symbol that nullifies a sharp or flat. It resembles a pair of sevens, the first upside-down and the second right side up, attached to each other front-to-middle. It looks something like this:


It is sometimes used in a key signature with a piece is written in a minor or diminished key, but usually occurs as an accidental preceding a note.

When a note is modified by a sharp or a flat in a key signature, that change continues throughout the piece; if it this is done as an accidental, it continues for the rest of the measure. In order to cancel this change, the note that was "sharped" or "flatted" is followed by a natural sign, which like other accidentals continues for the rest of the measure.

A natural sign looks something like this, when used as an accidental with a half note (a percent sign is probably the closest ASCII equivalent):

----| /--#-------------------------------------------------
   /|     #        % O                                     
 |  |  |            |                                      
  \ |  |            |