Cue "the more you know" jingle for this air travel public service announcement.
When your high-roller window seat is showing you nothing but dense cloud coverage, have you ever wondered what that little hole at the bottom of the window is for? Here's your answer. And listen closely, since this could totally be a question in your next pub trivia night.
That little thing is called a "breather hole," and turns out, it does two important things: It keeps warm air in between the windowpanes to ensure the outside chill doesn't get to you and the windows don't fog up; it also regulates pressure, so, ya know, the window doesn't explode. And if there's one place you DEFINITELY don't want exploding windows, it'd have to be an airplane. That shouldn't require explanation.