The concept of sheet music appears, at first glance, to be a simple on: music printed on large unbound sheets of paper. "Music," in this instance, refers to musical notation, a written system of symbols representing music. As far as it goes, this is a perfectly accurate definition of sheet music. However, there are actually several different subcategories of sheet music. If, for example, an instrumental piece is intended to be performed by more than one person, each performer is given a separate piece of sheet music called a "part." However, if the various instrumental (and often vocal) parts are printed together, then the sheet music is called a "score." And within the category of score, there is a wide variety of possible sheet music incarnations.

The term "full score" is used to refer to a large book containing all of the music for all of the instruments and voices in a composition. Such books are most often used by conductors, who need them to accurately and successfully direct performances. Similarly, a "miniature score" also contains all the music of a piece, but its greatly reduced size makes it impractical for use while conducting. It is more likely to be used by an individual who is studying a given composition. A "study score" may also be used for this purpose. Indeed, this score is often indistinguishable from a miniature score, but a study score is specifically intended for academic study and will sometimes contain extra comments for the edification of the reader.

A "piano score," as one might expect, is basically the literal transcription of a composition so that it may be played by one or more pianos (without the involvement of any other instruments). These scores are used for piano solos and piano duets and are often transcriptions of entire orchestral works. Needless to say, it is very difficult to express the music of an entire orchestra in the music of a single instrument, the result being that while there are a few exceptions, piano scores are performed mostly for study and pleasure.

A "vocal score" is similar to a piano score in that it reduces the full score of a vocal work, such as a musical or opera. Vocal scores are often accompanied by piano scores, as piano music is highly useful to a singer during rehearsal. Indeed, rehearsal is the most common use for a vocal score, during which time the sheet music allows the performers to learn their parts separately from the instrumental ensemble.

A "short score" is, to some extent the opposite of the piano and vocal scores. Granted, it is a reduction of a work intended for many instruments. However, in many instances, short score are actually created prior to full scores. Composers utilize short scores during the process of composing, using them to create a basic outline or sketch of a work that later, can be expanded for a complete orchestra.

Finally, a "lead sheet" and a "chord chart" are essential two parts of the same whole. The former specifies only the melody, lyrics and harmony of the music, while the latter provides detailed harmonic and rhythmic information.