Here, we have compiled a list of everyday things whose hidden potential can be extremely handy.
The copper buttons on your jeans are called rivets. They are placed at specific points that are most likely to tear apart from strain or movement.

The little holes in the windows of airplanes regulate air pressure difference between the inside and outside of the plane.

When placed upside down, the grooves allow water to flow rather than stagnate and spill over when you remove them.

The arrow next to your gas gauge shows which side the fuel tank is on.

Use the mirror tab to avoid those bright lights. Next time someone has their high beams turned on and blinds you through your rearview mirror, don’t forget to squeeze the tab on your rearview mirror so it tilts down. This way, the light is reflected downwards without impacting your field of vision.

The hole in the pen cap has nothing to do with the flow of air. It is actually implemented to reduce the risk of choking if someone swallows it by accident.
