The Normal Medium Arch foot type is the most common type of foot among runners. If you take a wet test the following images describe a Normal Medium Arch foot.
From the side a normal arch type foot should look like this image below.
Shoe type for Normal Arch Foot
According to Zappos website (No 1 shoe sellers) A runner with this type of foot should wear a stability shoe. These shoes have some medial support and good midsole cushioning. Because normal or medium arches are the most common foot type, most runners will need Stability shoes