“Over the last 100 years, you go from a point when a newspaper would be able to set the tone and the five top stories of the day, to what Walter Cronkite and his cohort would say on the evening news, and then to the explosion of cable news, and now the Internet,” says Gabriel Snyder, 36, the editor of The Atlantic Wire and former editor in chief of Gawker. “We’ve gone from having just a few handfuls of places that might set the agenda to this proliferation that is reaching a near infinite number of people who can define what the top story is today.”

Since many young people share on social media what they consume online, their notion of what makes an item good is tied to an outward, rather than inward-looking, set of priorities. “Media is now a way for readers to communicate, not just consume content,” says Jonah Peretti, 39, the founder of BuzzFeed who earlier helped to launch The Huffington Post. As he points out, people pause before sharing an article or video to ponder what it says about them that they are promoting it. “Social sharing is about your identity,” says Peretti. “You want to say, ‘Look, I’m smart, or charitable, or funny.’”

Callie Schweitzer, 24, director of marketing and communications for Vox Media, a fast-growing network of new online publications, agrees. “How we get and share news has become much more reflective of who we are,” she says. “People are proud to have gotten something first, and they want to be known for having found the cool piece of video first.” Also working to develop its editorial style with an eye toward shareability is Quartz, a business website launched last fall by Atlantic Media. Zach Seward, 27, a senior editor there, argues: “Putting the lede in the lede is burying the lede; get it in the headline! If there is a striking fact or statistic that tells the story, it should be the headline—the kind of thing you want to tweet.”

And what would you want to tweet? In essence, any factoid that a follower might find remarkable and therefore clickworthy. Pieces of content that pop on social media tend to have a certain “wow” factor. Editors routinely mention visuals—usually photographs, but sometimes charts or other graphics—as being enormously helpful in making something go viral in social media. Social-media companies agree. “Tumblr is a very visual medium,” says Mark Coatney, media outreach director for the image-friendly microblogging platform. “Twitter rewards words; Tumblr rewards visually presented info, whether great photography or graphics that grab your eye.”

Hard news—especially the depressing kind—is less popular than lighter lifestyle coverage on social media. “If you look at stories being shared, no one shares news,” observes Alex Leo, 30, head of Web products for Thomson Reuters Digital and a former senior editor at HuffPost. “No one ever emails ‘73 People Killed in Iraq.’ They email stories like ‘Sitting Kills You.’” Sure enough, on the day I spoke with Leo, The New York Times’s five most-emailed stories were a Style section feature called “The End of Courtship?”, a Travel section list of “46 Places to Go in 2013,” a column by Woody Allen riffing on hypochondria, and advice pieces on parenting and money management.

By posting observations and arguments on everything from personal blogs and discussion boards to Twitter feeds and comment threads, every young person is now, on some level, an amateur journalist. As bandwidth and connection speeds have increased, they are also publishing vast quantities of photos and videos with the help of services like Instagram, Flickr, and YouTube.

Increasingly, established news outlets are turning to these on-the-ground snippets of raw material to report on important social issues, from the Occupy protests to the presidential election. Twitter has famously been used for disseminating eyewitness accounts of events such as the Arab Spring uprising. Instagram, a swiftly growing service that is essentially Twitter for photographs instead of text, allows anyone to take a photo and effortlessly post it online. Instagram shots taken during Hurricane Sandy, for example, went viral on social-media outlets and were even published by mainstream news organizations.

Ben Adler covers climate-change policy for Grist and is a contributing editor for CJR