Facebook founder Mark Zuckerberg accepts an honorary Doctor of Laws degree from Marc Goodheart, Secretary of the Board of Overseers, during the 366th Commencement Exercises at Harvard University in Cambridge, Massachusetts, US, May 25, 2017. [Photo/Agencies]

NEW YORK — Mark Zuckerberg returned Thursday to Harvard, where he launched Facebook and then dropped out, telling graduates it's up to them to bring purpose to the world, fight inequality and strengthen the global community.

"Change starts local. Even global changes start small — with people like us," the Facebook CEO said. He shared stories about graduates such as David Razu Aznar, a former city leader who led the effort to legalize gay marriage in Mexico City, and Agnes Igoye, who grew up in conflict zones in Uganda and now trains law enforcement officers.

"And this is my story too," Zuckerberg added. "A student in a dorm room, connecting one community at a time, and keeping at it until one day we can connect the whole world." Such lofty talk now comes naturally to Zuckerberg, a 33-year-old billionaire who has committed to giving away nearly all of his wealth. In February, he sketched out an ambitious, if vague, vision for Facebook that committed the company to developing "social infrastructure" that would help build a "global community that works for all of us."

Zuckerberg, who like the graduates is a millennial, started Facebook in his dorm room in 2004. What began as a closed networking site for Harvard students is now a global communications force with nearly 2 billion members. Facebook's founding was the subject of a Hollywood movie, "The Social Network," in 2010.

Facebook's effect has been profound. It has connected people who would have never met otherwise, letting them form supportive networks online and offline. And it has allowed people to communicate in developing countries even if they don't have a phone number or a smartphone.

But it has also served to spread misinformation.