Excerpt from this article:
Facebook and Youtube reign supreme, with 61 percent and 55 percent of daily active users, respectively. Instagram and the Facebook-nemesis team over at Snapchat are neck-and-neck in the race for photo sharing apps (around 50 percent).
Signs are good for the beleaguered micro-messaging app, Twitter, with 35 percent, a trend that has seen dramatic growth over the past two years.
The sad panda award goes to Foursquare, with a self-reported zero-percent daily active userbase among teens (3 percent overall). Of course, there are certainly teens that use Foursquare daily, but not enough to be picked up in a pretty large survey.