Facebook announced Tuesday that it now has more than 2 billion users. Facebook, which was a social website available only to Harvard University students when it was launched in 2004, has recently been criticized for giving extremist groups an easy way to disseminate content over the internet. CEO and founder Mark Zuckerberg addressed the "Facebook community" after Tuesday's announcement and defended the social media website, saying that he was proud of the role his company was playing in connecting people around the world. Facebook's user base is bigger than the population of any single country, and of six of the seven continents. It represents more than a quarter of the world's 7.5 billion people. The company uses its huge size advantage to lure advertisers, offering them targeted marketing capabilities based on its data about users. The number of advertisers topped 5 million in April, the company said. Facebook's growth has increasingly come from outside the United States, Canada and Europe. Three years ago, those regions accounted for 38 percent of users; in the first quarter of this year, the figure was about 30 percent. To increase penetration rates in developing nations, Facebook has introduced stripped-down versions of its apps that use less data, and it has been developing solar-powered drones to extend internet connectivity around the planet. This report contains information from Reuters and AP.