On macOS, closing apps isn’t always as straightforward as it seems. Many new users are surprised to find that clicking the red button in the top left corner of an app window doesn’t fully close the app — it simply closes the window. The app itself often keeps running in the background. For example, here I have Safari running. If I click the red button on the top left corner, the window closes, but the app is still running.

The app remains active in the background and stays in the Dock with a small dot beneath its icon (indicating it’s still running).

To close the app fully, right-click (or Control-click) the app icon in the Dock. Select Quit from the pop-up menu.

This will close the app fully.

Further Reading

For more information on the subject, have a look at the following book: