As soon as a file is opened for editing, a copy of the page is created, the so-called working copy. All changes are made in the working copy during editing; only when the page is saved are the new/changed contents saved in the original page and are then published directly.
As long as the file is in editor mode and the editor window is open, the working copy is retained. The file is then locked and cannot be edited in parallel by other editors.
If the editor window is closed by clicking on the browser's close icon or if editing is ended in any way other than using the editor's function buttons, the working copy is retained. The file lock also remains in place and the changes are not published. Editors should therefore always use the editor's function buttons.
Unless otherwise specified manually in the system settings, a duration of 600 seconds is set for the lock.