Since about 2018, most new cars carry a forward-facing camera behind the rear-view mirror. It reads lane lines, watches the car ahead and triggers automatic braking. It's mounted to the windshield.
Replace the glass and the camera moves, usually by a millimeter or two. At 200 feet down the road that's a lane's width of error. Recalibration points the camera back to spec, either against a printed target board (static) or on a marked road drive (dynamic).
Skipping it can mean false braking, missed lane warnings or a dashboard fault. Every windshield we install includes it, with a printed report for your records and your insurer.