A theatre is a place (usually a permanent building) where plays and other performances are conducted. The word theatre can also describe, in general, anything related to what happens in a theatre. For example: Suzanne has run off and joined the theatre! or Robert's heart was always drawn to theatre.
A stage, often raised, was the focal point in a theatre. This can be on one end of the theatre, or in the center in the case of amphitheatres. This stage would be well-lit by natural light during the day, and well-lit by firelight and candlelight by night. A stage might have trapdoors to aid in special effects or movement of props or actors during a performance.
Theatres had seating (or lack thereof) organized by social classes. The poor were often left standing at ground level in an area center and close to the stage. Raised and balcony seating that ringed the interior of the theatre was available to nobility or those that could afford it.
Performing arts performed in a theatre included singing, plays (tragedies and comedies), musical performances and many others. In ancient and classical times, combat and gladiatorial contests and displays occurred in the theatre. Painters, sculptors and other artists were also employed in stage design and stage decoration.