A minuet is a stately ballroom dance for two people in triple meter. It is of French origin and was popular in the seventeenth and eighteenth centuries. Minuet also describes the musical style that accompanies the dance.
The early Baroque minuet was a simple binary form (A A B B), i.e., two-part form, and often used in dance suites. The gently driving triple meter and regular phrase structure hint at its social dance origins. Let's listen to a famous minuet from the early eighteenth century.
Minuet in G Major | Christian Petzold, 1677-1733, but sometimes attributed to J.S. Bach | Peter Kun Frary, 'ukulele
Minuet and Trio
Eventually the humble Baroque minuet evolved into a longer and more stylized form called minuet and trio. The minuet and trio was cast in ternary (A B A) form and used only for listening, drifting away from its dance origins. A typical minuet and trio form may be diagrammed thus:
Minuet
Trio
Minuet
A
B
A
a a ba' ba'
c c dc' dc'
a ba'
Note that the outer sections (minuet) are the same but the final minuet section omits the repeated sections. Modulation or mode changes are sometimes used in the trio section for contrast and tension. The minuet and trio is often used as a movement in symphonies, chamber music and solo sonatas.
The third movement of Mozart's Eine kleine Nachmusik, K. 525, scored for string orchestra, is a wonderful example of the minuet and trio. Here's the melody from the beginning of the Minuet (A section). Listen carefully and you'll hear it return after the Trio (B section).
A Section Melody | Mozart's Eine kleine Nachmusik, K. 525, Minuet
And the melody at the beginning of the Trio (B section):
B Section Melody | Mozart's Eine kleine Nachmusik, K. 525, Minuet & Trio
Eine kleine Nachmusik, K. 525 | III: Minuet & Trio | Wolfgang Amadeus Mozart (2:30)