What is Furcadia and how do you play

Furcadia is an online game available as a free download. You walk around the world as a pixelled avatar, and you can move freely throughout user-created 'dreams' (worlds) or make your own dream to share with visitors. There are a wide range of items, floor tiles and walls to pick from, or you can download others that people have made and use them instead, or even make your own.
Think of it as mainly an online chatroom, with much more to it than that.
Most people use the arrow keys to move around, and there are shortcuts to pick things up, use objects and teleport to different places.