How often do you read or post in anonymous online social media forums? Why do you think they are so popular? Do you think that kind of online anonymity can be dangerous? Why or why not?

In “Who Spewed That Abuse? Anonymous Yik Yak App Isn’t Telling,” Jonathan Mahler writes:

During a brief recess in an honors course at Eastern Michigan University last fall, a teaching assistant approached the class’s three female professors. “I think you need to see this,” she said, tapping the icon of a furry yak on her iPhone.

The app opened, and the assistant began scrolling through the feed. While the professors had been lecturing about post-apocalyptic culture, some of the 230 or so freshmen in the auditorium had been having a separate conversation about them on a social media site called Yik Yak. There were dozens of posts, most demeaning, many using crude, sexually explicit language and imagery.

After class, one of the professors, Margaret Crouch, sent off a flurry of emails — with screenshots of some of the worst messages attached — to various university officials, urging them to take some sort of action. “I have been defamed, my reputation besmirched. I have been sexually harassed and verbally abused,” she wrote to her union representative. “I am about ready to hire a lawyer.”

In the end, nothing much came of Ms. Crouch’s efforts, for a simple reason: Yik Yak is anonymous. There was no way for the school to know who was responsible for the posts.

Eastern Michigan is one of a number of universities whose campuses have been roiled by offensive “yaks.” Since the app was introduced a little more than a year ago, it has been used to issue threats of mass violence on more than a dozen college campuses, including the University of North Carolina, Michigan State University and Penn State. Racist, homophobic and misogynist “yaks” have generated controversy at many more, among them Clemson, Emory, Colgate and the University of Texas. At Kenyon College, a “yakker” proposed a gang rape at the school’s women’s center.

In much the same way that Facebook swept through the dorm rooms of America’s college students a decade ago, Yik Yak is now taking their smartphones by storm. Its enormous popularity on campuses has made it the most frequently downloaded anonymous social app in Apple’s App Store, easily surpassing competitors like Whisper and Secret. At times, it has been one of the store’s 10 most downloaded apps.

Like Facebook or Twitter, Yik Yak is a social media network, only without user profiles. It does not sort messages according to friends or followers but by geographic location or, in many cases, by university. Only posts within a 1.5-mile radius appear, making Yik Yak well suited to college campuses. Think of it as a virtual community bulletin board — or maybe a virtual bathroom wall at the student union. It has become the go-to social feed for college students across the country to commiserate about finals, to find a party or to crack a joke about a rival school.

Much of the chatter is harmless. Some of it is not.

“Yik Yak is the Wild West of anonymous social apps,” said Danielle Keats Citron, a law professor at University of Maryland and the author of “Hate Crimes in Cyberspace.” “It is being increasingly used by young people in a really intimidating and destructive way.”