Second Life is an online multimedia platform that allows people to create an avatar for themselves and then interact with other users and user-created content within a multi-user online virtual world. Developed and owned by the San Francisco–based firm Linden Lab and launched on June 23, 2003, it saw rapid growth for some years and in 2013 it had approximately one million regular users. Growth eventually stabilized, and by the end of 2017 the active user count had declined to "between 800,000 and 900,000". In many ways, Second Life is similar to massively multiplayer online role-playing games; nevertheless, Linden Lab is emphatic that their creation is not a game: "There is no manufactured conflict, no set objective."

In computing, an avatar is a graphical representation of a user, the user's character, or persona. Avatars can be two-dimensional icons in Internet forums and other online communities, where they are also known as profile pictures, userpics, or formerly picons. Alternatively, an avatar can take the form of a three-dimensional model, as used in online worlds and video games, or an imaginary character with no graphical appearance, as in text-based games or worlds such as MUDs.