TV dramas mainly focus on four genres: crime drama, medical drama, costume drama, and soap operas. Crime dramas and medical dramas both involve mysteries or problems that need to be solved. Soap operas typically have continuous storylines about relationships and feature working class characters. Costume dramas dramatize different periods of history and are often set in large country houses. Most genres follow conventions like having heroes and villains, but soap operas and crime dramas sometimes end on cliffhangers.