Developed and launched by Linden Lab on June 23 2003, Second Life is an online virtual world . There are several free client programs (Viewers) that enable Second Life users (Residents) to interact with each other through avatars. Residents can explore the world (the grid), meet other residents, socialize, participate in individual and group activities, and create and trade virtual property and services with one another.
As of 2011 Second Life has about one million active users
Avatars can take any form users choose (human, animal, vegetable, mineral) or residents may even choose to resemble themselves as they appear in real life. They can choose even more abstract forms, given that almost every aspect of an avatar is fully customizable. Second Life Culture comprises many activities and behaviors that are also present in real life.
Avatars can communicate via local chat, group chat, global instant messaging (IM), and voice. Chatting is used for localized public conversations between two or more avatars, and is visible to every avatar within a given distance. IMs are used for private conversations, either between two avatars, or among the members of a group. Unlike chatting, IM communication does not depend on the participants being within a certain distance of each other.
Second Life has an internal economy and internal currency, the Linden dollar (L$). L$ can be used to buy, sell, rent or trade land or goods and services with other users. Virtual goods include buildings, vehicles, devices of all kinds, animations, clothing, skin, hair, jewelry, flora and fauna, and works of art. Services include wage labor, business management, entertainment, "camping", and custom content creation.
L$ can be purchased using "real" currencies like US Dollars or £GBP on the LindeX exchange provided by Linden Lab, independent brokers or other resident users. Money obtained from currency sales is most commonly used to pay Second Life's own subscription and tier fees; only a relatively small number of users earn large amounts of money from the world. According to figures published by Linden Lab, about 64,000 users made a profit in Second Life in February 2009
Have a look at Second Life circa 2006: