Why do airplane windows have tiny holes in them?

Airplane windows are made of multiple acrylic layers for safety, and the tiny hole is in the inner pane. Its main job is to equalize cabin pressure between the inner and middle layers, so the outer pane bears most of the pressure difference at cruising altitude. The hole also helps prevent condensation and fogging between layers. This design improves durability and redundancy if a layer is damaged. The feature is common in commercial aircraft and is part of the aviation industry’s layered safety engineering.