There are several ways to leave IrfanView when you are
finished viewing/editing your images. The fastest, if
you are on the main window, is to press the ESC key on
your keyboard. This will close the program immediately.
(If you're in any of the menus or dialog boxes, ESC
will back out of that window. Press it again to exit.)
While the File Menu is open, you can press the E key,
to close IrfanView. (Open the File Menu by clicking it,
or by pressing the ALT key, followed by the F.) When
you use the mouse to click the File Menu, you can also
simply click the EXIT option to close the viewer.
In the upper left corner of the title bar, is the
IrfanView logo. Click this to bring up the standard
Windows control box. There are several options to
click; one of them closes the viewer.
Finally, you can use the mouse to click the Exit box in
the upper right corner of the IrfanView window. (It's
the farthest to the right in the very top row, as shown
below.) This will also close the program.
Be aware that IrfanView doesn't ask if you are sure you
want to exit - it assumes you really want to and closes
right away. Be sure you've already saved any work you
want to keep.