A theatre director or stage director is a professional in the theatre field who oversees and orchestrates the mounting of a theatre production such as a play, opera, dance, drama, musical theatre performance, etc. by unifying various endeavors and aspects of production. The director's function is to ensure the quality and completeness of theatre production and to lead the members of the creative team into realizing their artistic vision for it. The director thereby collaborates with a team of creative individuals and other staff to coordinate research and work on all the aspects of the production which includes the Technical and the Performance aspects.
The technical aspects include: stagecraft, costume design, theatrical properties (props), lighting design, set design, and sound design for the production. The performance aspects include: acting, dance, orchestra, chants, and stage combat.
If the production is a new piece of writing or a (new) translation of a play, the director may also work with the playwright or a translator. In contemporary theatre, after the playwright, the director is generally the principle visionary, making decisions on the artistic conception and interpretation of the play and its staging. Different directors occupy different places of authority and responsibility, depending on the structure and philosophy of individual theatre companies. Directors use a wide variety of techniques, philosophies, and levels of collaboration.
In ancient Greece, the birthplace of European drama, the writer bore principal responsibility for the staging of his plays. Actors were generally semi-professionals, and the director oversaw the mounting of plays from the writing process all the way through to their performance, often acting in them too, as Aeschylus for example did. The author-director would also train the chorus, sometimes compose the music, and supervise every aspect of production. The fact that the director was called didaskalos, the Greek word for "teacher," indicates that the work of these early directors combined instructing their performers with staging their work.