4. Read the text and give the main idea of each paragraph:

Second Life (SL) is a virtual world developed by Linden Lab that launched on June 23, 2003 and is accessible via the Internet. A free client program called the Second Life Viewer enables its users, called Residents, to interact with each other through avatars. Residents can play and be entertained, have relationships, meet other residents, socialize, participate in individual and group activities, and create, buy and sell virtual property and services with one another, or travel throughout the world (which residents call "the grid").

There is a three-dimensional modeling tool based around simple geometric shapes that allows a resident to build virtual objects. This can be used in combination with the Linden Scripting Language which helps add functionality to objects. Textures for clothing and skin of the avatars, animations and gestures can be created using external software.

Avatars may take any form users choose (human, animal, vegetable, mineral, or a combination of them) or residents may choose to resemble themselves as they are in real life, or they may choose even more abstract forms. A single resident account may have only one avatar at a time, although the appearance of this avatar can change between as many different forms as the Resident wishes. Avatar forms, like almost everything else in SL, can be either created by the user, or bought pre-made. A single person may also have multiple accounts, and thus appear to be multiple Residents.

Avatars can communicate via local chat or global instant messaging (known as IM). Chatting is used for localized public conversations between two or more avatars, and is visible to any avatar within a given distance. IMs are used for private conversations, either between two avatars, or among the members of a group, or even between objects and avatars. Unlike chatting, IM communication does not depend on the participants being within a certain distance of each other. Instant messages may optionally be sent to a Resident's email when the Resident is logged off, although message length is limited to 4096 bytes. If a message is sent to an offline Resident it will also be saved to be viewed when they log on.

In Second Life, residents buy and sell inworld real estate and goods, using a currency called Linden Dollars (L$). This means that residents in the virtual world can actually run profitable businesses (or make investments) that can be cashed out for “real” money (at the rate of 270 L$ to one dollar U.S.). Further, the avatars, property, and other in-world creations developed by users remain their intellectual property, not that of Linden Labs.

Linden Lab provides Second Life Viewers for Microsoft Windows 2000/ XP/ Vista/ 7, Mac OS X, and most distributions of Linux. The viewer renders 3D graphics using the OpenGL technology. Since the viewer is open source, users may recompile it to create their own custom viewers. Recently a client known as Emerald, created by a group of residents has become popular among the user base of Second Life due to the large number of features they have added to the original client.

Each full region in the Second Life "grid" runs on a single dedicated core of a multi-core server. These servers run scripts in the region, as well as providing communication between avatars and objects present in the region.

Nowadays more and more people join the virtual worlds, as they provide a great number of opportunities for their residents. Second Life has many applications in the modern world being used as a platform for education, scientific research, religion, sports, politics, economics and many other spheres of life. This proves that the ties between such virtual environments and “real” world society are becoming stronger every day.