Common Craft explains LinkedIn

What is LinkedIn? from LinkedIn Marketing on Vimeo.

Spotted on iLibrarian.

I think this can give you an idea and even explain networking. But the true benefit to LinkedIn, for job seekers, is that there are many human resource professionals on the site. Many of them are LIONs--many of them are not, and hate the idea. They pay a lot of attention to the Answers section, so you should be in there answering and asking questions, when relevant to your expertise. I have gotten recommendations from strangers, but LinkedIn connections, that I have been able to use in my work. You can use it in your job search, but you need a bigger network than other librarians and your college pals, so you have to make connections to people, usually by answering and asking questions.

That is the power of LinkedIn: you can expand your current network, which is limited by geography, and connect with people, linked to you by others or who ask to be introduced to you. But sitting passively on LinkedIn is not going to get you anywhere.