ABOUT SECOND LIFE™
SECOND LIFE IS A FREE ONLINE VIRTUAL PLATFORM
Second Life users, also called residents, create an avatar to interact with places, objects and other users. You can explore the world, socialise with other residents, listen to live music, create, shop, and more. Everything you see in-world was created by a residents.
The platform has its own currency, the Linden Dollar - shown as L$ -, exchangeable with real world currency. With it, you can purchase in-world goods, such as avatar customisation, objects, buildings, land, etc...
Note that Second Life is completely free to play, and there is also plenty of free goodies to enjoy.
To access Second Life (commonly called SL), you need an account and a viewer program, either SL's Official viewer, or a third-party viewer of your choice.