Sight reading is reading and playing a piece of music without having seen the sheet music before. The first reading of a piece that you intend to practice is, by definition, sight reading, but sight reading is also a useful skill to practice even if you don't intend to study a piece: it helps develop general musical skills, it gives the readers a quick idea of the piece, and it can be fun, too.

When singers sight read, it is called sight singing; if no lyrics are specified, they use solfege or numerical sight-singing.

Studio musicians (that is, musicians employed to record pieces for commercials, etc.) often record pieces on the first take, without having seen it before. Much of the music on television is played by musicians sight reading.

In some circumstances, such as examinations, the ability of a student to sight read is assessed by presenting the student with a short piece of music, giving the student an allotted time to examine the music and prepare to play the music, then testing the student on the proficiency of how the student plays.