That, says Judith Donath, a fellow at Harvard University’s Berkman Center for Internet and Society who studies social media and identity, is a real problem for young people.”There’s an enormous audience on social media, but it’s also when you see people face-to-face, you might see five people have heard something you know, thats basically the limit,” Donath said. “Online, it can extend in an infinite direction in both time and space.”

Source: In Rash Of Boston Violence, Shootings Follow Tensions On Facebook | WGBH News