A complete musical thought, concluded by a cadence, having two phrases, each usually two to eight measures in length, called the antecedent and the consequent.A time frame that encompasses a unique set of performance practices and styles. The main periods in Western music include Early Music (Pre-History to 600 C.E.); Medieval Music (Early Middle Ages - 600 to 1100 C.E. & Late Middle Ages - 1100 to 1450 C.E.); Renaissance (1450 to 1600 C.E.); Baroque (1600 to 1750 C.E.); Classical (1750 to 1825 C.E.); Romantic (1820 to 1900 C.E.); and Twentieth Century Music.The performance of a composition in the style, and often performed on authentic instruments, that are historicaly accurate to the time in history in which the composition was written.