If you're buying a gun from a store, you have to pass what's called a NICS check, to make sure you're not on a list of felons etc. that are not allowed to posse

If you're buying a gun from a store, you have to pass what's called a NICS check, to make sure you're not on a list of felons etc. that are not allowed to possess guns. In some states, you can buy a gun from an individual without a background check.