Cesar Sayoc -- suspected of sending homemade bombs to Democratic leaders throughout the country -- was an avid Twitter user. Twitter helped him connect with like-minded ideologues who reinforced radical views.

Some 85% of this key demographic use Instagram at least one a month, just edging out the 84% who use Snapchat on a monthly basis.

Messenger is awash in the automated software applications. More than 200,000 bots were now live on the service -- and they're becoming the preferred means for businesses to communicate with customers.

In this country, YouTube now derives 73% of its ad revenues from video, while Facebook dominance in the category continues.

Some 59% of teens say they have been the target of online bullies, while 63% say it is a major problem for people their age. Facebook is rolling out new tools to give users more control over how people interact with posts.