Second Life (SL) is an online virtual world developed by Linden Lab which was launched on June 23, 2003. A number of free client programs called Viewers enable Second Life users, called Residents, to interact with each other through avatars. Residents can explore the world, (known as the grid) meet other residents, socialize, participate in individual and group activities, and create and trade virtual property and services with one another. Second Life is intended for people aged 13 and over,[3] and as of 2011 has more than 20 million registered user accounts. Built into the software is a three-dimensional modeling tool based around simple geometric shapes that allows residents to build virtual objects. There is also an object oriented scripting language Linden Scripting Language which can be used to add interactivity to objects. More complex three-dimensional sculpted prims (colloquially known as sculpties), textures for clothing or other objects, and animations and gestures can be cr