This is an orchestral compostion, which is written is three separate movements, either for a single instrument or for a single instrument as dominant part with other instruments as background support, or for more than one instrument and orchestra.
Mozart wrote over fifty concerto’s for a variety of instruments. J.S. Bach wrote six concerto’s for the Margrave of Brandenburg in the years from 1719 to 1721.
Another form of concerto is the Concerto Grosso, which was very popular in the 18th century, and this was for a large group of instrumentalists to interplay with a smaller group. This phrase comes from the Italian and means big concerto.