Why closing the last window doesn't quit a Mac app

On a Mac, an app and its windows are separate things. Closing windows tidies your screen; quitting ends the app. Apple's own guide describes leaving apps open as useful for the ones you return to often, such as Safari or Mail, and an app with no windows can still be doing something for you: Music keeps playing, and Mail keeps checking for new messages.

The short answer

⌘W closes a window

Press ⌘W, or click the red button at the top left of a window, and that window closes. Apple's guide is explicit that closing one or all of an app's windows doesn't quit it: the app stays open, and the small dot below its icon in the Dock shows it. To close every window at once, press ⌥⌘W; closing all of an app's windows covers the other ways.

After its last window closes, the app is still the active one: its name stays in bold in the menu bar and its menus still work, so File › New, usually ⌘N, opens a fresh window straight away. In apps with tabs, such as Safari, ⌘W closes the current tab rather than the whole window.

⌘Q quits the app

Press ⌘Q, or choose Quit from the menu named after the app (Preview › Quit Preview). A normal quit lets the app finish what it needs to first, such as saving your changes. If the app had windows open, macOS shows them again the next time you open it, unless you turn on Close windows when quitting an application in System Settings › Desktop & Dock › Windows.

Apps that quit with their last window

Each app decides for itself. Apple's developer documentation describes the question an app is asked when its last window closes: quit now, or keep running? The app's developer picks the answer. Apps that work with many windows or documents, like Safari, Mail or Finder, keep running. Some apps built around a single window quit with it: close the System Settings window and the dot under its icon goes too. If you're not sure which kind an app is, close its window and look for the dot.

Finder doesn't quit at all: Apple notes that the Finder is always open. If it stops responding, choose it in the Force Quit window and click Relaunch.

How to tell an app is running

• The Dock: a small dot below an app's icon means it's open. If you see no dots at all, turn on Show indicators for open applications in System Settings › Desktop & Dock.
• ⌘Tab: hold ⌘ and press Tab to see every open app with a Dock icon, most recently used first. Press Esc before you let go of ⌘ to stay where you are.
• Force Quit: ⌥⌘Esc opens a window listing your open apps. You can close it without quitting anything.
• The menu bar: apps that run only from the menu bar show an icon toward its right end. They have no Dock icon and no place in ⌘Tab.

For the full picture, including background processes and Activity Monitor, see how to see which apps are running.

Does it matter?

For most apps, not much. Apple's advice is to quit an app you use only occasionally when you're done with it, especially if the app uses significant energy. To see which ones do, open Activity Monitor and click Energy: each app has an Energy Impact, a relative measure where lower is better, and an App Nap column.

App Nap is macOS's way of slowing apps you aren't using. According to Apple's developer guide, an app that isn't in front, isn't updating a visible window and isn't playing sound can be put in App Nap, which lowers its priority and fires its timers less often. Apple adds that this doesn't necessarily save energy; it mainly keeps idle apps out of the way of the one you're using. An app with no windows still holds on to its memory, which the Memory pane in Activity Monitor shows.

So keep the apps you return to all day running, and quit the ones you've finished with, or any app near the top of the Energy pane.

With Flick

Flick, a window switcher, shows a running app that has no windows as a single row with “No windows” under its name, so you can see what's still open without looking at the Dock. Pick the row and Flick asks the app to reopen, so an app like Finder or Mail opens a new window. To quit an app from the list, select one of its rows and press ⌥⇧Q while you hold ⌥, or ⌘Q with the ⌘Tab trigger; it's a normal quit, so the app can still ask you to save. Force Quit is in the actions menu, and asks first.

The rows come from Show apps without windows in Settings › General, on by default. Like the Dock and ⌘Tab, Flick lists apps with a Dock icon; menu bar apps aren't in it. In the free version, which lists your 5 most recent windows, an app without windows takes one of those places, so turn the setting off if you'd rather keep them for windows. Details are in change what Flick's list shows.

How to close, minimize, hide or quit from Flick