Maybe a Facebook invitation showed up in your email inbox and you’re trying to decide whether to join the site. Maybe you were alarmed when you heard your kids mention poking each other on Facebook. Maybe the Wall Street buzz caught your attention when Facebook—a whippersnapper of a website that didn’t even exist until 2004—clocked in at a breathtaking value of $15 billion. Or maybe you’ve noticed that Facebook mentions are regularly making it into your favorite local and national news programs.

However you heard about it, everybody seems to be talking about Facebook. And for good reason: In an astonishingly short period of time, Facebook has grown from an online yearbook for college kids to an Internet
juggernaut with over 400 million members. So what is Facebook, anyway? It’s a free-to-use, wildly popular socialnetworking site—which just means it’s a way to connect with other people—that combines the best of blogs, online forums and groups, photo sharing, and much more. By tracking the connections its members
make with each other, Facebook makes it easy to find and contact people—everyone from old friends and roommates to new customers, new bosses, and even folks you’ve never met before who share your interests.

Facebook The Missing Manual