What is the sharp sign used for in music?

In music, the sharp sign (♯) is used to raise the pitch of a note by one semitone. It is notated as a vertical line with a diagonal line through it, placed before the note to be raised. For example, if the note C is played with a sharp sign, it becomes C♯, which is one semitone higher than C.

The sharp sign is one of the five accidental symbols used in Western musical notation. The other accidental symbols are the flat sign (♭), the natural sign (♮), the double sharp sign (𝄪), and the double flat sign (𝄫).