Ah okay, this makes sense.
So when you’re heading on your holidays and take the standard picture out the plane window of the plane wing, have you ever stopped and wondered why the windows are round?
Is it just a design thing that plane designers learned in plane design school?
Well no, not quite, it’s a bit more technical than that.
As it turns out, plane windows were originally square. But in the 50s when jetliners started to become more popular, two planes fell apparent during flight with 56 fatalities.
See as expected, where there is a corner there is a weak spot. Four corners increase the chance of cracking due to air pressure. Naturally, with circles, the stress is distributed and the chances of cracking are reduced. Learn the science bit below.
https://www.youtube.com/watch?v=7rXGRPMD-GQ
Video via Youtube/RealEngineering 
