To read a disc, a laser beam shines up from below, through the plastic disc, reflects off a foil layer over data pits, then back through the plastic disc to a photodiode that reads the tiny variations in the light signal caused by the pits as the disc spins.
Scratches can block or reflect the laser beam from the intended path, making the disc unreadable.
Scratches on the bottom of the disc can be removed by resurfacing the disc. See our page on Disc Repair . AVS manufactures Disc Shields to protect your discs from damage and theft. Cover the vulnerable label side of the disc with a Disc Shield. AVS offers a full line of disc protective shields.