A tool composers readily employ for harmonic color and to make a passage's phrasing more striking.

A suspension elongates an individual chord tone's duration past when the actual chord moves on to the next one. This technique is the main source of all dissonance on any accented beat in tonal music.

A suspension will have a preparation, being the tone that precedes the suspension.

The suspension is sometimes tied to it's preparation, sometimes not. The suspension ends in a resolution, or the tone following the suspension and lying a 2nd below it.

The preparation and resolution are usually chord tones.