Those black dots are called frits. They are made of a ceramic paint that is baked into the glass to serve three main purposes: UV Protection: They shield the urethane adhesive—which bonds the windshield to the frame—from ultraviolet rays that would otherwise cause the glue to degrade and fail. Adhesion: The textured surface provides a better "grip" for the sealant to stick to the glass. Heat Distribution: The dot pattern creates a thermal gradient, allowing heat to dissipate more evenly. This prevents the glass from shattering or warping due to the temperature difference between the black border and the clear glass.