A quintet is a group containing five members. It is commonly associated with musical groups, such as a string quintet, or a group of five singers, but can be applied to any situation where five similar or related objects are considered a single unit. In classical instrumental music, any additional instrument (such as a piano, clarinet, oboe, etc.) joined to the usual string quartet (two violins, a viola, and a cello), gives the resulting ensemble its name, such as “piano quintet”, “clarinet quintet”, etc. A piece of music written for such a group is similarly named.