From www.mutopiaproject.org

In music, an invention is a short composition (usually for a keyboard instrument) with two-part counterpoint. (Compositions in the same style as an invention but using three-part counterpoint are known as sinfonias. Some modern publishers call them "three-part inventions" to avoid confusion with symphonies.) Well-known are the fifteen inventions that make up the first half of Johann Sebastian Bach's Inventions and Sinfonias. Inventions are usually not performed in public, but serve as exercises for keyboard students, and as pedagogical exercises for composition students.
The above text is available under the Creative Commons Attribution-ShareAlike License ( creativecommons.org/licenses/by-sa/3.0/ ). It uses material from the Wikipedia article "Invention (musical composition)" ( en.wikipedia.org/ ... ntion_(musical_composition) ).