I just received my MacBook Pro 13" Retina with 16 GB of RAM configuartion. I have only installed few minor programs like Chrome, Google Drive and etc. At the time of taking a screenshot (see attached) I did not run any programs. When I opened iStats Menus to browse around I saw that 8 GB of RAM is already being used. Why? Does it mean if I would have bought 8 GB of ram, the RAM would be fully used and apps would run slow. Please explain how everything works and why my number is already so high even though I just purchased the laptop. I know people use 4 GB of RAM and everything runs smooth. Sorry for such beginner's question; but I would really appreciate if you would explain to me how it works. Thank you!