Calibre is a FREE & open-source suite of e-book software for multiple platforms (Windows, Mac/macOS, Linux). Calibre supports organizing existing e-books into virtual libraries, displaying, editing, creating and conversion of e-books, as well as syncing e-books with a variety of e-readers...
It's the 21st Century -- what is your e-reader device preferred choice?
I still prefer actual physical books but I'm falling behind the times and it'd be nice to take advantage of stuff like Amazon Prime's "free" Kindle books. My wife already has her Kindle but I haven't picked up anything...