A heel is the bottom, back part of a shoe or boot that provides elevation. The styling and construction of a heel may vary (i.e., stacked, stilletto, spiked, sculptured, kitten).
About Mary Janes:
Mary Janes are shoes with a strap, or multiple straps, across the top of the shoe, usually right over the top of the foot. Mary Janes typically have rounded closed toes.
