It must seem crazy now, but a few years ago, it would only be possible to network with other like minded individuals by meeting them face to face at conferences and expos, but even then it would be impossible to meet all of the people that you would want to. Then came along Linkedin, this is place online where like minded people can connect and network without having to leave their office. Yet as with real life the idea is to have a cool enough profile that people are going to want to have to connect with you! Below is a graphic compiled by Lab 42, they asked five hundred US based Linkedin users how they used their profile as a networking tool, the answers have been carefully placed into this graphic below.
Source [Lab 42]