From outside in. And from inside out. You can open a window to let the smell of perfume or gunpowder escape. It is even possible to dispose of a dead body out a window. Or you can hide behind the drapes when someone comes home unexpectedly and you've been searching the place.
Windows are very useful.
Window , Text Nr. Famous defenestrations include one in some political-type building in Prague some years ago. I don't know how many. Go ask Frank, the fish. When God closes a door, He opens a window somewhere.