Since I bought my Macbook, i noticed that after you close an app like Firefox on OS X, it doesn't really quit the application. I can tell its "still there" because of the little arrow next to its corresponding icon on the Dock. I always wondered why that was. Now days, i always quit the app by pressing Apple+Q. I was wondering if its better to close apps or actually quit them, every time you're done with them for the moment.