Facebook is an online social network, consisting of about 1,32 billion active users. On Facebook you can share pictures, status updates and follow pages that you find interesting. It was founded in 2004 by Marc Zuckerberg, when he was in college. Facebook was meant to be a site where college students could communicate and keep in touch with each others, but it spread and became popular world wide.
I think that Facebook have become an important part of our daily life. A large amount of the population has joined this community, and it makes it easier for them to communicate. I think many people would say that if you do not have a Facebook-account you would be a little outside of the community, because so much is happening online.
Source: Wikipedia (link)