Orchestra

http://en.wikipedia.org/wiki/Orchestra

An orchestra is an instrumental ensemble. In an orchestra, it consist of sections that is divided according to the instrument family that is string, brass, woodwind, and possibly a percussion section. The orchestra grew by accretion throughout the eighteenth and nineteenth centuries, but changed very little in composition during the course of the twentieth century.

To form an orchestra, a necessary amount of players are needed. For smaller orchestra it must consist about fifty players or fewer where it is called a chamber orchestra. A full size orchestra must consist about 100 players and it may sometimes be called a "symphony orchestra" or "philharmonic orchestra".

In the organisation of the orchestra, there are principle in every section where they are resposible for orchestra solos. The principle of the strings is also considered as the concert master. In modern times, musicians are usually directed by the conductor.