Roleplaying games are a type of theatrical play, supported by occasional board game mechanics. They´ve enjoyed a rising popularity in the last years.
Roleplaying games offer a varied set of themes. From stone age, to medieval times or fantasy, space exploration, to dystopia or modern - that and a lot more.
Like other games too, roleplaying games follow a set of rules. Each rule system differs a lot. Some systems set very light rules to offer maximum freedom.
Often (not always, though) roleplaying games need a game master or some form of moderator to decide outcomes or to present a plot. Sometimes these game masters ask their players for a roll of a die. Sometimes a game master can´t choose, but the situation in the game demands a roll. Most of the times it´s a combat situation, in which miniatures are used on a game board.