Window or aisle? When it comes to where to sit on a plane, location matters. If you are the kind of person who loves traveling by the window, then chances are you have noticed the small hole at the bottom of the airplane window and wondered why they are there. This tiny hole actually has two purposes.
First, it serves to compensate for air pressure. There is a huge difference between the inside and outside of the airplane when the plane is at cruising altitude, so in order to regulate this difference and avoid the windows from breaking due to too much pressure building inside, the holes allow airflow through. The second reason is for it to prevent the window from fogging up.