Short answers, pulled from the story.
Pantomime is a type of musical comedy stage production designed for family entertainment, combining fairy tales, slapstick, cross-dressing, and audience participation. It is performed primarily during the Christmas and New Year season throughout the United Kingdom, Ireland, and other English-speaking countries, a tradition rooted in 18th-century English theatre.
Pantomime traces its origins to ancient Roman performance traditions, the word itself derived from the Latin pantomimus and the Greek meaning a dancer who acted all the roles. It developed further through the 16th-century Italian commedia dell'arte, 17th-century English masques, and early 18th-century London theatre productions at Lincoln's Inn Fields Theatre and Drury Lane.
Joseph Grimaldi was a performer who dominated London pantomime in the early 1800s and transformed the role of Clown into a colourful agent of chaos, as important to the entertainment as Harlequin himself. His performances were praised for their acute observation upon the foibles and absurdities of society, and he is credited with expanding the harlequinade until it dominated the pantomime entertainment.
The last harlequinade was played at the Lyceum Theatre in 1939. After Parliament removed restrictions on spoken drama in 1843, the silent harlequinade gradually lost ground to the fairy-tale opening of the pantomime, and by the end of the 19th century it had been reduced to a brief epilogue of dancing and acrobatics.
The convention that the villain enters from stage left, and the good fairy from stage right, traces back to medieval mystery plays, where the right side of the stage symbolised Heaven and the left side symbolised Hell.
According to Kitty Gurnos-Davies's doctoral dissertation, pantomime accounts for 20% of all live performances in the United Kingdom in any one year. The 2018-2019 season saw pantomime performances generating over £60m for the first time in recorded British history.