Basso ostinato

Ostinato, an Italian word meaning "stubborn" (compare English obstinate), is to classical music what riffs are to popular music.

An ostinato is a bit of melody, a chord progression, or a bass figure that is repeated over and over as an accompaniment. Ostinato commonly vary as repeated, most often through rhythmic extension, truncation, or displacement, but must remain identifiable. Ostinati are frequently used in Baroque music, where the basso continuo invites the use of the technique (as a ground bass), and fixed forms such as the passacaglia and the chaconne require it. The left hand in boogie woogie piano playing is another.