One of the first things that the human race did was social networking. The earliest men networked and bonded into tribes to their mutual benefit and the security it offered them. As the human race grew and became more sophisticated, so did the way in which these networks developed and the social network definition came to include guilds, brotherhoods, trade unions and so on. This evolution continued until it developed into the form of social networking that we know today.
How networking was done changed with the arrival of the internet and the definition of social networking also changed. The accepted modern definition of social networking is the action of expanding the number of people a person knows to further their social and business interests. The arrival of the internet meant that this network was no longer limited to people one met physically and then continued to have contact with on various levels, including physical meetings. Today a person sitting at home with his computer can meet and establish a longer term link with almost anyone, anywhere.
The ease with which millions of people all over the world can be accessed has brought the theory of Six Degrees of Separation into prominence. This is a theory which postulates that with the almost unlimited access that a person has to others, it is possible for any person, anywhere to get in touch with anyone else on the planet through the use of 6 intermediaries - one person puts you in touch with the next and so on until the desired person is contacted. This has changed the whole definition of social networking and it is no longer just a matter of creating or joining a group of like minded people - social networking today is about being able to contact anyone, anywhere. While this maybe theoretically possible, for most people the definition and application of social networking is more limited.
Most people use social networks to link to those whom they feel they should know, either for business of personal reasons. Besides establishing contacts online, a person who joins a social network usually invites his friends to join. These friends in turn ask their other friends to join and soon a network of linked people is established that continues to grow organically as people continue to bring in others after they join. In other words, the definition of a social network today is that of a set of people with linked interests and objectives who may not necessarily ever meet in person, but are able to work together and help each other in achieving their individual and group goals.