I am struggling to keep up with my readings especially the ones I need to read for classes I am taking and also the journal publications. Some of these papers are longer than expected and I feel terrible printing them and killing all the tress!! Lehigh keep showing a reminder on the desktop in Windows 7 machines to inform how many trees we kill when we print. Also I keep making notes on papers and filling my room and office with papers that I read once and never use it again( at least for now), so I stated looking for an easy more environment friendly solution to this issue. Initially I was thinking of an e-book reader or a tablet but later realized that I can do some basic stuff with my MacBook Pro too. Here is my solution.
Annotate the PDF file, using Preview on Mac.
But if you are on a Mac, you may not realize that you can annotate PDF files for free using Preview. When you are looking at a PDF file on the Mac in Preview, go to the Tools section of the menu bar and select the Annotate option. It should look like this…

Using these commands, you can add notes, links, and shapes to the PDF document to mark it up. And don’t worry about others being able to read the changes, they can. When you annotate a PDF file in Preview and save your changes, they can be read by other Mac users as well as by users using Adobe Acrobat on a PC. Apple doesn’t really tout this feature much, but if this is great functionality to have for free when compared to most PC users.