Frits and Dots

The black dots on windshields and windows and the black rims that surround them, are more than decoration.
From the 1950s and 1960s onward, car manufacturers began using an adhesive to hold car windows in place, rather than metal trim.
The black rims around car windows are called “frits.” The frits and the dots that border them are made from ceramic paint. The frits are there to hide the adhesive. These painted rims are baked into the window and hold the glue in place, which in turn holds the windows in place.
The dots are there to make an aesthetically pleasing transition from the thick black lines to the transparency of the window. They are positioned in a halftone pattern, getting smaller and farther apart as the black recedes. This pattern is less jarring to the eye than opaque black paint juxtaposed with transparent glass.

Their other purpose is to provide temperature control. To get the glass of windows and windshields to be bent the way it is, the glass is heated up. The black-painted glass heats up faster than the rest of the window. The dots distribute the heat a bit more even and prevent the windshield from warping in the heat.