A virtual world created by a company based out of California known as Linden Labs. The world takes the form of a collection of "sims" owned by players which cost an amount of rent to LL per month. Each sim is based off of a physical server at LL headquarters. In-world money, known as lindens can be exchanged to real world money (most world currencies) and it is this fact that makes Second Life so successful. Unlike other MMOGs (massive multiplayer online games), Second Life offers the opportunity for the acquisition of real world profit.
I just got rich selling virtual shit that doesn't even do anything on Second Life.