In the last six months or so, there's been an increase in press, buzz, and hype about virtual worlds and online games (often referred to as MMOGs, for Massively Multiplayer Online Games). The most successful of these --- the most popular virtual world, Second Life, and the most popular MMOG, World of Warcraft --- have had the highest profiles What are they, and why are they gaining momentum?

Virtual worlds are computer-generated and defined environments. They can be 2D, 3D, or even text only (as the first ones were). More than a simple chat room or instant-messaging program, they provide a sense of space and place for people to interact via computers. Generally, members are represented by an avatar, a graphic representation that they have named and customized to represent them. The virtual world that's received the most visibility of late is "Second Life."

Second Life is a 3D environment that allows its customers (or residents, as Second Life calls them) to build and program what goes into the world, a major source of its popularity. As a result, Second Life offers a crazy quilt of experiences and spaces for all of its residents. In Second Life, you can find reconstructions of real-world cities like New York and Seattle; historically accurate reconstructions of Egyptian cities and tombs, collections of walk-thorough sci-fi film props, and any imaginary space the residents can imagine.

While Second Life itself is not a game, there are ways for residents to build zones for gameplay, from live-action role-playing to shoot 'em ups to games of chance.

A lot of social-action work goes on in Second Life. The American Cancer Society's Relay for Life has run virtually in Second Life, raising money for the organization and giving participants a tour of some of Second Life's most interesting venues. A virtual Darfur refugee camp has run in the space, and numerous resident-devised political and social-action events have been mounted as well.

Corporations have been testing Second Life as an advertising and sales-generation tool; recently Scion ran a promotional campaign by sprinkling virtual cars around Second Life. Dell Computers has a giant virtual computer built into "Dell Island." Numerous colleges and universities are building virtual campuses and other types of educational and training spaces in Second Life, including an entire virtual hospital for medical simulations.

One of the things that's driven Second Life buzz the most is an economy and currency that can be translated into real-world cash, allowing residents to build anything from clothing for avatars to full simulations and sell them to others for real-world cash. A number of Second Life residents have been able to make their second life be their real job and support their first life. A few are even successful enough to generate six-figure incomes. There are also "mature" environments and practices that occur within Second Life, and there's a way to block those sites and content if you don't want to see them. And there's a whole separate, monitored space so the underaged can experience the freedom of a virtual world without some of its vices.

Second Life's surge in popularity prompted MTV recently to announce three virtual worlds that it's creating, one of which is patterned on the Laguna Beach television show. All three are built on software designed by there.com, another virtual world.

An MMOG is a virtual world built for a game. Here, people run their avatars through sword and sorcery, film noir, and science-fiction environments to build increasingly powerful avatars to overcome increasingly difficult challenges (slay the dragon, gain control over a solar system, etc.) This gameplay usually requires teamwork, and old and new friends join together in guilds or teams to play together. Current king of the hill is the World of Warcraft (WOW, to its players), an outgrowth of a stand-alone computer game into an on-line world. Roughly nine million players world wide are paying $50 or so for the initial software and then $15 a month to play. The game's development company, Blizzard, Inc., just released an expansion set to the game called "The Burning Crusade," which popped it back up in the news.

On WOW, players can fight monsters or each other for virtual loot and more powerful armor, swords, spells, etc. Unlike Second Life, MMOG operators generally don't allow players to make money off of their gameplay or build original items within the game. There is, however, a virtual "black market" of people who advertise the sale of virtual currency, characters, or equipment external to the game. This, too, has created a "real" economy from a virtual one. This is allowing some players of these games to create viable second and first incomes from their gameplay.

This barely scratches the surface of what's happening in virtual worlds and MMOGs, and it's a topic I'll be coming back to. If this has piqued your interest, here are some things to look at:

Virtual worlds: Second Life, There, and Virtual Laguna Beach.

MMOGs (most of these offer two-week free trials, either off their websites or via your local game store): WOW, Space Opera, andSuperheroes.

Want a better grasp on the bigger picture? Try these books:

* "Synthetic Worlds: The Business and Culture of Online Games," by Edward Castronova. Castronova is the economist who undertook the study of on-line games as a joke and, to his surprise, discovered thriving economies larger than those of many real-life countries. He's currently gotten funding from the MacArthur foundation to build a virtual world-game based on the works of Shakespeare.

* "Play Money: Or, How I Quit My Day Job and Made Millions Trading Virtual Loot," by Julian Dibbell. Technology journalist Dibbell has been covering this field for years. His book is a more personal account of his experiences than Castronova's, which is a broader look at the potential impacts of these spaces. Dibble wrote the groundbreaking Village Voice piece "A Rape in Cyberspace" over a decade ago. You can read it here.

* "Second Life: The Official Guide," by numerous authors: a guide to Second Life in general and how to get started there in specific.

Where to find me: Last but not least, here are names and places, in which my virtual selves can be found.

* Second Life: Noir Gumshoe (I drop in a few times a week).

* WOW: Blood Elf Hunter Hemotional on Eitrigg (I'm generally playing once a day)