The game client is free and open-source download. There is no charge creating an account and an avatar. But there iis an option for upgrading to a (Premium Account) for a fee. This will enable the user access to more services such as: buying and trading virtual real estate, creation of multiple avatars and more.
Intel powered Mac (1.5GHz or faster)
Mac OS X 10.6 Snow Leopard or newer
OpenGL compliant graphics card
Broadband Internet connection
Free download at secondlife.com