Why are there lines on the rear glass of cars?

Question

Answer 1

The lines on rear glass of the car are not simply there for aesthetics. In fact, they are the elements to heat the rear glass in cold conditions, by doing so they remove the fog which gets accumulated on that, or they de-fog the glass. Hence, poppet known as de-fogger. These days it is a standard feature in most of the cars.

Answer 2

Those 'orange lines' you see on the rear windscreen of cars are actually the heating elements for the rear window defogger. The defogger's function is to help get rid of any condensed dew water on the rear windscreen by heating it mildly.