Take the example of Facebook. It was launched in two thousand four as a social network just for Harvard students.

VOA: special.2009.09.14

Now anyone can join. Facebook said it had over two hundred fifty million active users as of July.

VOA: special.2009.09.14

Facebook started as a site for college students to share interests and information.

VOA: special.2010.05.28

as in a friend you accepted on Facebook?

VOA: special.2009.09.14

The question has to be 'How do we maximize the value of the traffic that we're going to receive?'" For a lot of advertisers, internet advertising, social networking sites such as Twitter or Facebook, and internet searches on sites such as YouTube can be the answer.

VOA: standard.2010.01.27