In its infancy, the internet was thought of as a social network, mainly because, in theory, anyone connected to the internet could communicate with anyone else. In practice however, very little communication could be easily done until the advent of social networking software. Social networking software first became common in the last 1990s with the ICQ application, one of the first chat programs to use the model on which all are now based.
The fundamentally different thing that ICQ did, and the thing that has made social networking software so popular, is assigning an ID number to every user - like a phone number - and, more importantly, have every user log onto a central server when he or she used the application. It is this second aspect that was fundamental for social networking software. What it meant is that users could create a list of "friends" - others who used the software - and could be notified when their friends were online and could be accessed through the network. This allowed social networking software to become completely distinct from email, as people easily and regularly could communicate to each other live. Without this notification of when friends were online, most of the popular aspects of social networking software would be ineffectual.
After social networking software became more common and popular, the next step began the advent of the social networking site, which allowed people to meet each other easily. Before the social networking site existed, it was rare and rather difficult to meet people online. IRC and other primitive chat rooms existed, but there was no way of knowing who anyone was, and no real interaction beyond publics chatting.
A social networking site usually allows people to post profiles and pictures of themselves, in much the way a personal ad would function. Because of the large amount of people who use these sites, people of all interests and types, a user can literally search for what he is looking for and quickly get in touch with someone who shares his or her interests. When the social networking site is combined with social networking software, the possibility of the internet playing a major role in most people's social lives in the near future starts to seem very strong. After using a social networking site to find someone the user believes he or she will be compatible with, the social networking software can be used to chat with the person.
If they get along, two people may spend hours chatting on the internet before meeting in real life, greatly increasing the chances of a positive experience with the real life meeting. Social network software also provides the ability for people who already know each other personally to easily stay and touch and communicate in real time for free over long distances.
For many people, chatting to a far away friend using social networking software is a more special and personal way to stay in touch then with email, yet doesn't incuring the high costs of a long distance phone call. With more and more people using social networking software every day, there is no doubt it will affect all of our social relationships in the future.