Ten years ago today, Chad Hurley, Steve Chen, and Jawed Karim, three former employees of PayPal, registered a new company devised around a simple idea: that there should be one website where people can upload and watch videos. At the time, this goal was ambitious. Finding videos online was a pain, something Karim discovered when looking for footage of Janet Jackson's "wardrobe malfunction" at the 2004 Super Bowl and that year's Indian Ocean tsunami. For two months, the site contained no videos and attracted little attention. Then, on April 23, Karim uploaded a 19-second clip of himself standing in front of the elephant exhibit at the San Diego Zoo.

"They have really really really long, uh, trunks," he said. "And that's cool."

The video wasn't exactly Oscar-worthy. But as the first ever YouTube video, it's certainly historic—and has been viewed more than 17.5 million times in the years since. YouTube is now the third-most viewed website in the world, boasting over one million viewers who watch more than 6 billion hours of footage each month. Each minute, users upload 300 hours of video to YouTube's servers. And despite its reputation for hosting clandestine home videos that go viral, 29 of the site's 30 most watched clips are professionally produced music videos. For popular music fans, YouTube is this generation's MTV.

YouTube—which Google purchased for $1.65 billion in 2006—is a phenomenally successful entertainment medium: The site is now valued at $40 billion. But YouTube has also greatly influenced both the production and consumption of news across the world. Seven years after Jawed Karim's failure to find video footage of the Indian Ocean disaster, the 20 most popular YouTube videos showing the 2011 tsunami in Japan were viewed nearly 100 million times. The following year, the Pew Research Center found that 39 percent of all videos used by news organizations depicted raw footage shot by civilians. Amateur video has provided news consumers with valuable information from Syria, a country whose violent civil war has driven professional news organizations away.

YouTube videos have played a significant role in many major world events. In Iran, footage of the death of Neda Soltan, a young protester, went viral and accelerated the country's anti-government demonstrations in 2009. More recently, the Islamic State has relied on Internet videos for propaganda purposes. Earlier this month, ISIS released a film showing Muadh al-Kasasbeh, a Jordanian pilot held hostage by the group, burning to death in a cage. The video sparked widespread outrage in Jordan, whose government promptly vowed retaliation. Online video did not create terrorism—but it reduced the barriers to entry for groups like ISIS to broadcast their message.

"Extremists don’t need a middleman anymore," wrote Jeffrey Goldberg in the Atlantic last December. "Journalists have been replaced by YouTube."

The meteoric rise of YouTube, Facebook, and Twitter has bolstered the dreams of idealists who want to use technology to solve the world's problems, a point of view frequently skewered by skeptics like writer Evgeny Morozov. While YouTube's spread has allowed people to see the world from more points of view, the powers of democratized video can only go so far in pushing along change. The Iranian government survived the 2009 protests without making any significant concessions, and hopes that the social-media-lubricated "Arab Spring" movements would bring lasting change to Egypt, Yemen, Syria, and Libya have been similarly dashed. China, which, like Iran, blocks YouTube, has had little difficulty censoring domestic equivalents.

But the examples of Iran and ISIS show that the fundamental innovation encapsulated by YouTube's motto—"broadcast yourself"—has permanently changed the landscape of journalism. Any individual with a smartphone and Internet connection now possesses a tool once reserved by television networks. Not a bad legacy for a site that started with a 19-second elephant video.