Virtual Worlds for kids are more than just websites. They are destinations, places to play, to meet friends, hang out and participate in a community.
Some Definitions:
Virtual Worlds: a computer-based simulated environment intended for its users to inhabit and interact via avatars. (wikipedia)
Avatar: is an Internet user’s representation of himself or herself. (wikipedia)
MMO: Massively Multiplayer Online Game, a computer game capable of supporting hundreds or thousands of players simultaneously. (wikipedia)