I've been trying to discover a good definition of digital activism and I think I've found it courtesy of Frank Edwards, Philip N. Howard and Mary Joyce in their study Digital Activism & Non-Violent Conflict released on November 13th.
We define a digital activism campaign as an organized public effort, making collective claim(s) on a target authority(s), in which civic initiators or supporters use digital media.
The study also concludes something I've argued for a long time, ever since the increasingly irrelevant pop philosopher Malcolm Gladwell implied that digital campaigns were simply lazy millennial 'slacktivism':
Digital activism has demonstrated, positive impact on drawing people to the streets to protest, especially when civil society groups use digital tools and changing government policy is the goal.
Well-organized and disciplined social and digital campaigns work.