What is a "key signature"?

A key signature is a crucial musical notation that consists of a set of sharp or flat symbols placed at the beginning of a staff. It indicates the key of the piece, which defines the scale and the tonal center around which the music is organized. Understanding the key signature is essential for musicians, as it informs them which notes will typically be sharp or flat throughout the piece, thereby affecting the overall sound and harmony. This system helps musicians perform with accuracy and cohesion, as it sets the tonal framework for the composition. Recognizing the key signature allows singers and instrumentalists to interpret the music correctly, leading to a unified performance.