What causes nail pops in drywall and how can they be prevented or fixed?

Nail pops in drywall are caused by the movement of the wood framing behind the drywall, which can push the nails out over time. To prevent nail pops, use screws instead of nails when installing drywall, ensure the framing is properly secured, and use adhesive along with fasteners. To fix nail pops, simply drive the nail back in and cover with joint compound.