Let's find out the reason here.
If you have been traveling through planes often, you might have observed that the windows of the plane are round or slightly curved. But have you wondered why the windows are round and not rectangular? The answer behind the round shape of windows is quite interesting.
Check out the answer here!
With the progress in technology, the size of the plane was changed along with the shape of windows in order to carry more passengers.
The reason was the square shaped windows.
Rectangular windows have four corners which mean it has four potential weak points which can crash down under stress.