If you’re chatting on Yik Yak, it’s pretty much guaranteed that you’re a millennial, talking with other millennials.

comScore’s 2015 US Mobile App Report looked at which apps have the highest concentration of millennials. Another way of putting that it which apps count 18 to 34-year-olds as the majority of their userbase.

And what comScore found was that millennials tend to dominate many popular social apps.

Yik Yak, a location-based messaging app, can count millennials as a staggering 98% of its adult userbase.

Mobile payments app Venmo is 94% millennial, while Tinder and Snapchat count 18 to 34-year-olds as 79% and 76% of their adult userbases, respectively.

“What nearly all of the apps in the ranking above have in common is a social element to them. Even apps that serve non-social functions, such Venmo with payments or Spotify and SoundCloud with music, have integrated social add-ons which are crucial to the value proposition of those apps. Expanding further on the social theme, the list also includes several social personalization apps, such as InstaSize and Layout from Instagram, which indicate Millennials’ affinity for creative expression and enhanced communications,” says comScore

If you’re looking to advertise or promote content on Snapchat, Vine, Tumblr, or Spotify – it’s definitely worthwhile to know your target audience. And that target audience, by and large, is between 18 and 34 years old.