Musical notation in written or printed form.
Sheet music, also known as a score, is a printed or sometimes handwritten document representing a piece of music using musical symbols. Typical sheet music consists of a staff (pl. staves) containing musical notes, and a clef establishing the pitch represented by the position of those notes, along with other musical symbols. Often, sheet music also contains information about the composer of the piece, and the piece itself.
The process of reproducing sheet music is called engraving, a historically manual and mechanical process which is now often done with computer software (using a graphical interface, or another notation scheme such as LilyPond).