There are two, good and bad. first we'll discuss good ones,
by using internet we can find many answers related to subject. so many websites are there to clarify doubts like brainly.in etc.knowing many things, improving our knowledge, knowing about history, world affairs, inventions, discoveries, can read biographies about great personalities, exact information about anything etc.
BAD:- teens are addicted to facebook, watsapp by chatting with others for hours, watching videos which are bad, always watching cinemas in net etc.
hope this helps plz mark it as best..........