When we enter a virtual world, we are making an agreement to play by a new set of rules. Those rules emerge from a mixture of elements. The “rules of the world” (everything from its physics to its user interface) provide a structure for participants, while the emergent culture defines a set of cultural norms or mores which provide the community with another set of rules, values, and meanings. What makes virtual worlds special is that both of these elements depart from the conventions of the physical world.