positive impacts of social media on teens?

[Spicy]

Very broad question
Social media provides a quick, easy way to share and distribute information. Which can have many applications.

Networking:
Able to maintain and manage extended networks of acquaintances much easier and for a longer time - even after phone number / address changes.

Organizing Events: Study sessions, parties, etc.

Sharing files: Better able to share documents, files, images. This includes digital textbooks, diagrams, even full recorded lessons and educational videos.

Education / Professional: podcasts and webinars are now a common way to distribute information. For example: the Structural Engineers Association of California regular hosts Webinars on topics such as Seismic Retrofitting of Unreinforced Masonry Buildings - March 15, 2012

Entertainment: I'm sure I don't have to explain this one to you.

Crime: Unproven, social media has a correlation (not causation) with decreased crime (murder, rape, etc).
USA copyright infringement is illegal, but not a criminal offense. (Correct me if I'm wrong, law is not my field)

etc.etc.etc.

The hard question isn't positive effects, it's what's the negative effects of social media on teens?