It seems just about everybody has a mobile phone now, including more than three-quarters of U.S. teens and a rapidly growing number of younger kids. For young people as well as adults, the technology has changed the way we work, play, communicate, learn, and socialize. Even the term “smartphone” is a bit of an understatement, with all that its hundreds of thousands of applications allow us to do—track flights, do homework, stay fit, take tutorials, avoid traffic, find recipes, read books, or share moments and play games together across vast distances.