But instruction and entertainment aren't the only reasons fans log on. Both Lee and Nguyen say that YouTube and Instagram influence their shopping habits as well. "When I'm looking for new products, I will either go to Sephora's website and look at the new releases, or go to the drugstore and look around at what is new," Lee explains. "Then, I'll make a mental note of what products seem promising, and look up their reviews on YouTube or a beauty blog." Nguyen's routine is similar. "I mainly will remember products, or write down ones I think I'll like, that I hear or see a blogger mention," she says. She'll even go so far as to check out reviews on her phone when she's in-store.Moore says that this is common practice for YouTube-video viewers. "When viewers learn about a product, it might help them narrow down their decision before they purchase," she says. It's a far cry from where things were just a decade ago. Counter gals and guys were the resources if we were looking for product recommendations, and we typically found new swag on the faces and in the makeup bags of our friends and family members.All of this access to information has created savvy consumers — and increasingly younger ones. "If you look at the statistics of beauty content, the 13-year-old mark is typically where we see [viewership begin]," Moore says. Pixability's research found that 50% of beauty-content viewers on YouTube are females between the ages of 13 and 24. "The majority of viewers we see are starting [to watch] in their teen years, which is definitely younger than we thought," she explains. "Another matter is when you're looking at the beauty blogger [filming the video], her typical viewer is several years younger than she is. As [someone like] Michelle Phan matures and talks about more mature beauty products, her audience is trailing behind her — sometimes between five and seven years."That's where it gets a little hairy. Do we really want 13-year-olds learning the fine art of contouring? Is it truly necessary for girls in middle school to be imitating the fully made-up faces of 25-year-olds on Instagram?Gwenn Schurgin O'Keeffe, MD, CEO and editor-in-chief of Pediatrics Now , says that the influence of social media on children is much greater than most people realize. In fact, a study by Common Sense Media found that children as young as preschool-age are concerned with the way they look — and it's because of what they see on television and on social media. That same study found that 87% of female TV characters aged 10 to 17 are below average in weight — and those portrayals can affect children's perceptions of themselves.