from a rock chip you can have it stopped if you catch it early. The rock chip repair guys can do a repair at the end of it and "fill" it with the resin that they use. I had mine done for $15 today using a coupon from the back of the telephone book. Muuuuch cheaper than a new windshield.

I am so happy that they have the technology to repair now rather than replace, I drive lots of highway miles so I am always at risk for a chip in the windshield. It is a much better solution than replacing it.