The term Sustain (səstén) refers to holding a note while playing the guitar. The way sustain is held will shape a guitar player’s style. The sound of the sustain can be affected by a few things; thin, light strings will not provide a rich sounding sustain the way thick strings will.

The sound of the sustain is a key factor in the quality of instruments. A light, inexpensive guitar will provide a thinner sounding sustain, but a heavy, good-quality guitar will provide a rich, full sustain. Sustain can also be generated by an effects pedal.