By the time Tina was 14, she was navigating deals with brands and moving from small-scale promotions to sponsored posts on her Instagram and YouTube pages, which now boast more than 500,000 followers each. These days, brands send 17-year-old Tina (who asked that I only use her first name) so many makeup products that they practically flood her apartment. “I get sent a couple packages daily, so there’s a lot that I either give away or never even get to try out,” Tina said. Tina is one of many influencers in an ever-expanding framework that links the social and commercial. Influencers — experts in their own niche arenas, from makeup and beauty to veganism — cultivate relationships with their audience, a unique feature that allows them to advertise with the perceived authenticity of recommendations exchanged between friends.