* Key signature: A set of sharps or flats placed at the beginning of a staff to indicate the key of a piece of music.
* Time signature: A set of numbers placed at the beginning of a staff to indicate the number of beats in a measure and the note value that gets one beat.
* Clef signature: A symbol placed at the beginning of a staff to indicate the pitch of the notes on that staff.
Keys
* Major key: A key that has a bright, happy sound.
* Minor key: A key that has a dark, sad sound.
* Chromatic key: A key that uses all twelve notes of the chromatic scale.
* Pentatonic key: A key that uses only five notes of the chromatic scale.
* Modal key: A key that is based on one of the seven church modes.
Each of these signatures and keys can be used to create a unique sound and mood in a piece of music.