Remember when you were little and you used to play dress-up or "pretend"? Role Play is a tad of that. RPs were once allowed in one of the Forums on Foo, the description read:
This forum is ONLY for Role Play this includes all simulated play of animals and persons, Wolf packs, Unicorns, Looney institutions, and any other role playing games. Role Play is allowed only in this forum.
There are many different forms of RPing, where you take the role of a character you created & with a few other members you act out a story each being your own character & this RP will develop a plot by the different events. Wikipedia says this is "collaboratively create stories" "involving anywhere from two to several hundred people". So a group-story... Roleplaying is a way for people to express themselves and their creativity while having fun at the same time.
Lots of fansites now have RPing, due to Foo deciding that all forms of RPing would not be permitted & deleting the forum that had been used for this. All old RPs were also deleted because of a few RPs bad behavior. Here is just one fansite that has role play in it: http://theawesomerp.webs.com/