1. Pitch Modification: A sharp (#) is a musical symbol that indicates a note should be raised in pitch by one semitone (half step). It is placed before the note name to be modified, such as C#, D#, or G#. For instance, if you have the note C, adding a sharp (#) would make it C-sharp, which is a half step higher than C.
2. Key Signature: In music notation, a sharp can also be part of a key signature. A key signature is a set of sharps or flats placed at the beginning of a staff to indicate the key in which a piece of music is written. For example, the key signature of G major consists of one sharp, F#, which indicates that all F notes in the piece should be played as F-sharp.
Sharps are commonly used in Western musical notation to provide precise instructions on the pitch of notes within a musical composition. They allow composers and musicians to create melodies, harmonies, and chord progressions with specific intervals and tonal relationships.