It always surprised when people asked me ‘You also know LinkedIn?!’… I mean… when those professional asked me. I was also one of them who is confused on what is LinkedIn but I get to create an account since 2010 and is exposed on the door of opportunities it can open me to…
According to http://en.wikipedia.org/wiki/LinkedIn, LinkedIn is a social networking website for people in professional occupations.
You can always sign up for an free account on http://www.linkedin.com/home, it helps you connect to a lot of people of the same professional as you can join in groups which you are interested in… usually professional group – to find a job you might be interested or to get headhunted.
Good luck in your career and future~