Humans talk and trade.
Face to face meetings were the earliest form of networking. It was so good, we still use face to face meetings as a major part of our social and business lives.
Writing gave us another way to tell our stories at a distance.
The printing press gave us a new way to talk and tell stories.
Then the telegraph, the telephone, radio, TV, CB radio, PCs, email, the internet, and the World Wide Web.
The internet began as a tool to share information. In past few years, we see a new phenomenon, the rise of social media. This video is a great introduction to the rapid growth and influence of social media.
Think of social media as your new network. Twitter is your conversation, more like talking to people you meet. Your blog is more static and tells a story about you and what you do, a brochure and more. Facebook is where you are more relaxed and informal. Talk with your friends. Keep up with what they are doing and thinking.