A toccata is a free-form composition for a keyboard instrument, typically featuring virtuosic passages and improvisation. It originated in the 16th century and was a common form in the Baroque era. Toccatas are often used as preludes or introductions to other pieces, such as fugues or chorales.
Fugue
A fugue is a contrapuntal composition in which a short melody (the subject) is introduced and then imitated by other voices (the answers) in a series of overlapping entries. Fugues are typically written in three or more voices, and the soggetto is often developed and transformed throughout the piece. Fugues were a prominent form in the Baroque era and are often associated with the works of Johann Sebastian Bach.