Is yak the new cashmere? Stylish guys are seeking out the thick, shaggy wool of the Asian ox for softness and durability—and the way it lets them casually say, ‘Actually, it’s yak.’ ...

The famous, and infamous, app that rocketed to popularity in 2014 is back. It's still anonymous, but there are lots of rules about what you can post.

Yik Yak, which started in 2013 as a way to connect students on campus and quickly rode its way to one of the top 10 most-downloaded app charts, grew to $400 million in market value.

Incidents of social-media bullying and threats by teenagers highlight the risks of new anonymous mobile-messaging apps like Yik Yak, which has rapidly become popular on the nation’s college ...