Art of leading a group of musical performers.
Simple coordination of a group does not always require a conductor (members of a Renaissance choir kept together by one tapping another on the shoulder, for example, and musicians in a recording studio listen to a "click track" on headphones). Before с 1800, the first violinist usually gave the few necessary signals with his bow; the keyboard player might also lead the orchestra, using his hands and head. In the 19th century the larger size of ensembles and growing complexity of music, including its varying tempos and heightened expressiveness, made it necessary for a person to coordinate and interpret the music for the group. The first conductors, including Felix Mendelssohn , Hector Berlioz , and Richard Wagner , were composers themselves. By the end of the 19th century, conducting had become a specialty and the great conductors had become celebrities in their own right.