What is reverse polarity?
Reverse polarity is one of the easiest issues in electrical wiring to correct. Basically there are two wires connected to the outlet that need to be reversed to correct the problem. It takes only a couple of minutes.
Most outlets have either two prongs or three prongs. The two prong have a hot slot and a neutral slot; the three prong have a hot slot (usually the short vertical slot), a neutral slot (usually the long vertical slot) and a ground slot ( the circle shape, flat on one side).
Reverse polarity can result in being shocked under a few conditions and may result in damage to an electronic device. In most case you can plug a fan or light into an outlet that has reversed polarity and it works, however, correcting the wiring on an outlet that has reversed polarity is still recommended.
So simple to fix
Usually just reversing the hot and neutral wire will correct the polarity. Generally the neutral wire will be a white colored wire and the hot will be any color except white or green. i.e. black, red purple, brown, blue, etc. On most outlets the wire holes are marked, or there is a gold and silver screw. The gold screw is for connecting the hot wire and the silver screw is for connecting the neutral wire.