A concerto as a musical work is a composition usually in three parts or movements, in which (usually) one solo instrument (for instance, a piano or violin) is accompanied by an orchestra. The etymology is uncertain, but the word seems to have origin from the conjunction of the two Latin words conserere (meaning to tie, to join, to weave) and certamen (competition, fight): the idea is that the two parts in a concert, the soloist and the orchestra, alternate episodes of opposition and cooperation in the creation of the music flow. The concerto, as understood in this modern way, arose in the Baroque period side by side with the concerto grosso, which contrasted a small group of instruments with the rest of the orchestra.