An organ concerto is a piece of music, an instrumental concerto for a pipe organ soloist with an orchestra. The form first evolves in the 18th century, when composers including Antonio Vivaldi, Johann Sebastian Bach and George Frideric Handel wrote organ concertos with small orchestras, and with solo parts which rarely call for the organ pedal board. During the Classical period organ concerto became popular in many places, especially in Bavaria and Austria (whether called there a concerto, pastorella, or sonata), reaching a position of being almost an integral part of the church music tradition of jubilus character. From the Romantic era fewer works are known. Finally, there are some 20th- and 21st-century examples, of which the concerto by Francis Poulenc has entered the basic repertoire, and is quite frequently played.