"Sci-Hub is a shadow library website that provides free access to millions of research papers, without regard to copyright,[4] by bypassing publishers' paywalls in various ways."
<https://news.ycombinator.com/item?id=33698018>
<https://news.ycombinator.com/item?id=20781277>
<https://news.ycombinator.com/item?id=17652359>
(The /r/dredmorbius links in the comments linked above may be seen at the Internet Archive, as that subreddit has been taken private in protest of Reddit's recent policy direction.)