CD & DVD Discs
Dirty media can cause errors or make the media not work at all. You can remove fingerprints and dirt by lightly rubbing with a clean lint-free cloth. Cotton is the best material to use. You need to wipe starting at the middle of the disc and work your way to the outer edge. Never wipe in the direction of the tracks (the lines running around the disc). If the dirt is harder to remove, like dried on liquids for example, use water or a spot of rubbing alcohol on a cotton swab to clean it. You can also purchase disc cleaning kits.
Never use a general all-purpose cleaner on a disc.