I’m quite pleased with the selection they chose, it seems to be focused quite extensively on cryptography and privacy initiatives. I am somewhat surprised they haven’t donated to EFF, but they did manage the OpenBSD Foundation and the Tor Project, which I am very pleased with.
User nominated list, though I’m not sure how they actually select. Last year they donated to the EFF to support work on Privacy Badger.
Where does the DDG revenue come from?
If my counting is correct, that was something like ~225K donated.
Ads and affiliates. If you don’t have an ad-blocker enabled, you’ll see search ads at the top of results, similarly to how Google or Bing do it. Though they don’t appear on every search, and aren’t as numerous as Google/Bing currently do things (maybe more like Google circa 10 years ago). And they specially add affiliate links to some kinds of links, I think mainly Amazon.