Have you ever been sitting in an airplane and looked out the window only to think, “Why the hell is there a hole in it?” We have too. But don’t worry, it’s not part of some greater illuminati scheme. No, it’s there for our safety.
According to Travel + Liesure, The little hole in the bottom center of every airplane window is called a breather hole, and it keeps the pressure between the window’s inner and outer panes equalized. So if anything ever happened to the window, the outside panel would give out and the inner one would theoretically remain intact, allowing you to breath. It also keeps the window fog-free, as to never obscure vision (both for safety and the view).
So now you know, and you never need to wonder again. Just sit back, and enjoy the flight.