Two-thirds of online teens surveyed said they tell friends about products — that's almost twice as many as adults — and more than 70% of teens use social networks regularly. So it's critical for marketers to understand how to best use social networks to reach teens and to help them spread the word. Teens use social networks primarily for entertainment and communication, and tapping into entertainment users, who are also cross-category influencers, is key. Social networks can be a hub for cross-media "cool" and a launch pad for modern integrated campaigns.