A short history: 


Pantomime was first performed in England as short acts between Opera pieces. These were later turned into full performances as they were so successful, they were considered as a form of opera. It is believed that The Lincoln's Inn Field Theatre and the Drury Lane Theatre were the first to stage something like real pantomimes. The first ever real pantomime was performed in the Drury Lane Theatre and was called 'Harlequin Doctor Faustus'

What is pantomime? 

Pantomime is a musical comedy production performed on stage. It was desiged for family entertainment. Modern pantomime includes songs, slapstick comedy and dancing, employs gender-crossing actors, and combines topical humour with a story loosely based on a well-known fairy tale. Pantomime includes a lot of audience involvement, including shouting out 'boo', 'hiss' and 'he's behind you!' Sing alongs are also frequent. It took inspiration from the theatre convention Comedia dell arte.

Conventions: 

The principal boy The male juvenile lead - for example Aladdin or Cinderella's Prince Charming. He's always played by a young woman (lately, usually a television celebrity) in a tight costume.

The Panto Dame Almost always played by a man in drag, the panto dame is a comic, and camp, female character. She's usually an older woman but in Cinderella, not only the step mother but also the Ugly Sisters are panto dames. In Aladdin (at more than 200 years old, one of Britain's oldest panto stories) it's Aladdin's mother, a poor laundress known as The Widow Twankey. Popular comedians and occasional famous leading actors with a sense of fun often do a winter turn as a panto dame.

A side kick or "chorus" figure: There is always a secondary character on stage who speaks to the audience, encouraging them to shout and clap or comically commenting on the action. In Cinderella that character is Buttons, her father's (Baron Hardup) servant and her friend. In Aladdin it is Wishee Washee, the hero's brother.

A comedy animal: Most pantos feature a comic animal played by two actors in one costume. In Jack and the Beanstalk, Jack's cow is a Panto cow. If the plot of a story doesn't have a place for an animal, you can be sure that the panto writers will shoehorn one in.

Lots of audience participation: When you go to a panto in Britain, you can't help but be drawn in to the traditional shouting and carrying on. Villains are hissed, misfortunes are bemoaned and several key lines - "Oh yes it is!" - "Oh no it isn't!" and "He's behind you!" are shouted out by one and all at the appropriate moments.

Contemporary references and bawdy jokes: Pantos are family shows but there is usually enough innuendo of the nudge-nudge wink-wink variety to keep the grownups happy.

A transformation scene: Most pantos have a moment when the set designers bring out their most magical special effects - twinkly lights, disappearing characters, clouds of smoke. Every story has its traditional transformation scene - Cinderella's emergence in her ball gown with her coach and footmen, Aladdin's discovery of the genii in the cave of jewels.