I learned on OSX an app doesn't close when you close the window, you have to quit it. Seems like very strange behavior - e.g. I closed Safari but can cmd-tab to it, nothing shows up on screen except a change in the menu bar. I can only conclude that all Mac users must learn to do this naturally? I see no reason to keep an app alive - if it needs to so something in the background, it should be a system service. Does OSX not close the app so it can be launched quicker next time? That's what caching is supposed to do, otherwise it just consumes resources. AFAIK no other OS does this - Windows or Linux.