Short answers, pulled from the story.
The Oxford English Dictionary defines role-playing as changing one's behavior to fulfill a social role. This core concept captures the essence of assuming different behaviors for specific purposes.
Modern improvisational theatre began in classrooms with the theater games of Viola Spolin and Keith Johnstone in the 1950s. Viola Spolin insisted her exercises were games involving role-playing as early as 1946.
Kurt Lewin conducted classic social psychological experiments in 1939 that assigned participants to particular roles. Stanley Milgram utilized this method in his famous research during 1963, and Phillip Zimbardo employed similar techniques in his landmark study published in 1971.
Role-playing occurs online through group story creation involving anywhere from two to several hundred people. Public forums, private message boards, mailing lists, chatrooms, and instant-messaging services build worlds lasting hours or years.
The ancient Romans, Han Chinese, and medieval Europeans all organized events where everyone pretended to be from an earlier age. Entertainment appeared to be the primary purpose of these historical activities.