On the playa, almost anything goes. Self-expression, in any form that doesn't go against the festival's 10 principles (see sidebar), is a good unto itself and may include creation or destruction, drugs, sex or nudity, improvised or lovingly planned performance, or large-scale sculpture hauled hundreds or thousands of miles on a truck bed. People build such things for the occasion alone.
The 10 principles impose few limits. They're a lot about removing limits, in fact -- removing limits and encouraging responsibility -- for one's world, one's neighbors and oneself.
In this limitless community, there is no such thing as going too far. Walking around the playa, a Burner might see anything -- like a 45-ton (45-metric-ton) house shaped like an elephant, or a front porch pulled by a tractor, both 2012 features [source: Pisillo, Burning Man]. Back in 1998, Burners may have seen a forum for fighting radio-controlled vehicles; in 2005, the festival featured something called "Barbie porn"; and in 2008, a theme camp dedicated to offering such things as advice popped up.
Theme camps, art, gifts and activities might spring from the year's theme, like 2009's "Evolution" or 1999's "The Wheel of Time." Burners themselves provide concerts, theatre, bars, art exhibitions and group meals. There are guided spiritual journeys, drum circles, weddings, funerals and sex clubs on the playa.
In the spirit of radical self-expression, some of Burning Man is R- or X-rated. Most of it, however, is not, and many families do attend the festival. Theme camps, for their part, will often post signs if they are not child-appropriate. Ultimately, though, Burning Man may not be the place for those easily offended or shocked. Burners who bring their kids should be OK with their children possibly seeing some adult (or just very, very odd) sights.
Thinking of joining in? A few practical issues to consider before hitting the Burning Man playa ...