A form of sheet music, usually written by hand. The
arranger/
composer/band leader will pass lead sheets out to his group of musicians so that they may properly play a tune.
Lead sheets are not very specific however; normally they just contain the correct number of notated measures and repeats with the
key signature, the
chord which is happening in a given measure, and any emphasized sections or notes the player should be aware of.
They are extremely popular in
jazz and
pop music, especially in the studio for efficient read-throughs and in live performance for
reference.