Following the sudden death of her husband Dave Goldberg, the Facebook COO published a heartfelt tribute to him online - which was shared more than 330,000 times within two days of its appearance.
A children's charity says "it is time for social networking sites to be held to account" after a "disturbing" video was posted on Facebook showing a baby being dunked in water.
Convictions for internet "trolls" who target people with abusive or offensive material online increase eight-fold in a decade, official figures reveal.
As party leaders head to their local polling stations, millions of people take to Facebook and Twitter to let their friends know they have voted, encouraging others to do the same.
Two young activists have been taking very different approaches to youth engagement at this general election.