From the company's webpage:
Free Realms is a free 3D virtual world where you can do whatever you want, whenever you want! Jump in straight from your web browser! Once you create your character, you'll be in and playing in just a few minutes.
Decorate your house, then invite your friends over for a party! Teach your pet a new trick or dress them up in a sweet costume! Battle enemies as you search for lost treasure or duel other players, mine for gold, cook up a meal, or race your car! When you're ready for a different kind of challenge, play a wide variety of fun minigames, jump into the trading card game or check up with your friends on your profile page. Free Realms is the place to join up with your friends to discover, explore, compete, chat, share achievements and just have fun! In Free Realms, YOU RULE.