Chord-playing musicians (e.g., those playing guitar, piano, Hammond organ, etc.) can improvise chords, "fill-in" melodic lines and solos from the chord chart. It is rare for chords to be fully written out in music notation in pop and traditional music. Some guitarists, bassists and other stringed instrumentalists read accompaniment parts using tabulature (or "tab"), a notation system which shows the musician where on the instrument to play the notes. Drummers can play accompaniment by following the lead sheet, a sheet music part in music notation, or by playing by ear.