From Wikipedia, the free encyclopedia:

A role-playing game (RPG; often roleplaying game) is a game in which the participants assume the roles of fictional characters and collaboratively create or follow stories. Participants determine the actions of their characters based on their characterization, and the actions succeed or fail according to a formal system of rules and guidelines. Within the rules, players can improvise freely; their choices shape the direction and outcome of the games.

An example

Say, the players decide to be musketeers in 16th-century France. One of them is designated a game master; his job is to devise a suitable challenge (perhaps a plot against the king), and all the necessary details, such as significant locations, events, secondary characters, etc. The other players create a protagonist each, and play their parts to bring the adventure to life. The GM describes the situations that arise and decides the outcomes of their actions. The rules can be very simple ("use you common sense!") or very complex, based on math formulae and rolling dice.

There are many ways to practice role-playing; I prefer freeform style and play-by-post, but MU*s are fine, too, and I don't mind a little randomness.

(For the modern, busy player who may have a hard time finding and keeping a local gaming group, virtual tabletops look like an attractive option. But it's an option I haven't tried yet.)

Current projects

Battles & Balances
A rule system for computer RPGs, written as if for tabletop.
Tales of Space and Magic
a science-fantasy setting with freeform rules based on my stories.
Annotated RPG Links
My annotated list of tabletop RPGs.

My past games

Starting Small
An aptly named adventure set in a deliberately generic fantasy world.
The Treasure Hunters of Mega
A space opera adventure set in the Megaspace.

Reference material

Articles, reviews and forums on a variety of RPG-related topics.
Story Games
A good forum and newsletter about tabletop RPGs.
Roleplaying Tips
Newsletter and articles for both aspiring and experienced game masters.
John H. Kim's Role-Playing Game Page
A long-time roleplayer's personal home page.