What is typically found at the beginning of a sheet of music to indicate the key?

The key signature is typically found at the beginning of a sheet of music and serves to indicate the key of the piece. It consists of a series of sharp or flat symbols placed on the staff that denote which notes are to be played sharp or flat throughout the piece. This vital information helps performers know the tonal center of the music and understand the scale the piece is based on.

By knowing the key signature, musicians can interpret the music accurately, enhance their playing, and anticipate the mood or character of the piece, making it essential for effective performance. In contrast, a time signature denotes the rhythmic structure, a clef indicates the pitch range or staff used for reading the music, and a measure refers to the actual division of time in the music.