So I'm trying to find the best software to use to take notes in college. I've searched google but I couldn't neccesarily find one that allows me to download PDF lecture slides and to be able to edit them and write notes on them. Anyone have any suggestions on what application can accomplish this? I've heard that Evernote, Devonthink, Omnioutliner etc are good but I'm not sure if they allow you to edit PDF lectures slide files as if a word document lecture file would allow. Any help would be appreciated. example--I currently use word to take notes in class but my professor puts up PDF files of lectures slides (the ones that have 3 slides on a page along with lines next to the slides) so I was looking for a way to just write on those lines next to the slides(on the pdf file) instead of opening up word to write whats on the slide plus my extra clarification/ notes.