"Second Life" is a free-access online virtual world developed by a San Fransisco-based company that had approximately one million users in 2013. "Second Life" users, called residents, create virtual representations of themselves, called avatars, and are able to interact with places, objects and other avatars. They can explore the world (known as the grid), meet other residents, socialize, participate in both individual and group activities, build, create, shop, and trade virtual property and services with one another. The platform principally features 3D-based user-generated content. "Second Life" also has its own virtual currency, the Linden Dollar, which is exchangeable with real world currency.