About Windscreens:

A  windscreen is made up of two pieces of glass that are separated by a layer of 'PVB' (polyvinyl butyrate) that essentially 'glues' the two pieces together:

This has several benefits, the most important being that it acts as a barrier in the event of a crash because the windscreen is held together when fractured:

This layer can also help the windscreen block out harmful UV rays, can add some tinting, and can help reduce the amount of sound that comes through the windscreen:
Modern, glued-in windscreens contribute to some of today’s vehicle's rigidity:

In the event of a damaged windscreen, the two options are to repair or replace:
Originally, a damaged windscreen had to be replaced, but that was very expensive so windscreen repair became common:
Repairing is often desirable because it keeps the original factory installation of the windscreen:

Our windscreen replacement service operates, replacing cracked or damaged windscreens, smashed windscreens and other auto windscreens and auto glass: