An early form of conducting is cheironomy, the use of hand gestures to indicate melodic shape. This has been practiced at least as far back as the Middle Ages. In the Christian church, the person giving these symbols held a staff to signify his role, and it seems that as music became more rhythmically involved, the staff was moved up and down to indicate the beat, acting as an early form of baton.
By the early 19th century, it became the norm to have a dedicated conductor, who did not also play an instrument during the performance. The size of the usual orchestra expanded during this period, and the use of a baton became more common, as it was easier to see than bare hands or rolled-up paper. Among the earliest notable conductors were Louis Spohr, Carl Maria von Weber, Louis Antoine Jullien and Felix Mendelssohn, all of whom were also composers. Mendelssohn is claimed to have been the first conductor to utilize a wooden baton to keep time, a practice still generally in use today. Amongst prominent conductors who did not or do not use a baton areLeopold Stokowski, Pierre Boulez, Dimitri Mitropoulos, Kurt Masur, Leonard Bernstein and Nikolaus Harnoncourt. Hans von Bülow is sometimes considered the first professional musician whose principal career was as a conductor.
Hector Berlioz and Richard Wagner were also great conductors, and they wrote two of the earliest essays dedicated to the subject. Berlioz is considered the first virtuoso conductor. Wagner was largely responsible for shaping the conductor's role as one who imposes his own view of a piece onto the performance rather than one who is just responsible for ensuring entries are made at the right time and that there is a unified beat.
Conducting requires an understanding of the elements of musical expression (tempo, dynamics, articulation) and the ability to communicate them effectively to an ensemble. The ability to communicate nuances of phrasing and expression through gestures is also beneficial. Conducting gestures are preferably prepared beforehand by the conductor while studying the score, but may sometimes be spontaneous.