Answer:
When theatre was first 'invented' in ancient Greece, plays took place in enormous stadiums outdoors and only men were allowed to portray characters onstage, so masks were used to define each character, especially those that were women. Over time, masks became more and more elaborate. To show the masks off to the audience members, actors would face straight out rather than facing their fellow actors onstage. This eventually became known as "off-stage focus". Ancient Greek and Roman theatre was either comedy, involving light-hearted themes, or tragedy, in which most characters died.
Theatre in ancient Italy was called Comedia d'ell Arte, also using masks, and was always very farcical in content. The same types of characters were used so often that the masks became known as those personalities. When this became well-known, artists stopped writing scripts and instead made up the story as it went along. This is known today as Improvisation.
Today, one can see any type of theatre in any number of facilities, with both genders performing scripts that range from absolute farces to serious melodrama to anything in between. Theatre has changed very much, but one can still see the connections to it's ancient roots.