Sheet music is a written recording of music which is transcribed in music notation. You could think of sheet music like a book; musicians can read sheet music to visualize a musical composition, and the sheet music can be played out loud just like a book can be read aloud. Reading sheet music also requires a unique form of literacy, as the ability to read musical notation requires some education. Various stores which focus on musical instruments and performance sell sheet music, and it can also be purchased directly from companies which specialize in printing sheet music.
Music notation is a powerful tool. By using music notation, a composer can record a piece as he or she has envisioned it, and a musician anywhere in the world can read the notation and reproduce it. In addition to including the literal notes of the piece, music notation also includes lyrics and notations which provide directions on how the piece is to be played. Humans have been using music notation for a long time; the earliest known example comes from around 2,000 BCE, when music notation was used on a cuneiform tablet.
For people who do not know how to read music notation, a piece of sheet music can seem totally mystifying. The most common method of modern musical notation involves a staff, which has fine lines on which individual notes can be written. The shape and style of a note indicates the duration, and the staff has notations to tell people which key the piece should be played in, and the tempo. For a musician, these small markings represent sounds which can come together to make anything from a solo guitar composition to an orchestral piece.
There are a number of different types of sheet music. In an orchestra, for example, each musician does not have the entire score. Instead, musicians have parts, which indicate when they should come in with their instruments and what they should play. The conductor of an orchestra has an entire copy of the score so that he or she can keep track of the piece as it is played; a conductor's score for even a brief symphony is incredibly dense. Sheet music can also be made for vocal parts. A “chord score” is used by jazz musicians and other freestyle musicians, and it focuses on harmonic information rather than the melody of a piece.
The first sheet music produced on a printing press emerged around the 1500s. Sheet music was difficult to produce on a movable type press since it integrated a number of elements which required multiple passes. With the use of lithographic plates and other modern printing tools, it is relatively easy to produce sheet music, and what was once rare is now readily available.