The term shoe drop generally refers to the difference in thickness of the sole of the the shoe from the heel to the toe area. The extreme descriptive example is the women’s high heel shoe. Running shoe drop, also known as heel to toe differential, among other terms, is a much more subtle difference. This can range from zero drop where there is no difference from heel to toe to high drop, which can be up to 12mm difference from heel to toe. Drop can be further classified with low drop being 1-5mm and medium drop 6-9mm differences. What drop a particular person should choose is based on a number of factors including planned activities, running style, joint range of motion and injury patterns. Running style is typically classified by foot strike pattern, heel strike, midfoot strike or forefoot strike. In general, heel strike runners can benefit from higher drop shoes owing to the thicker material in the heel to absorb shock. Midfoot midfoot and forefoot strikers can benefit from lower drop shoes for a more even strike and faster cadence. Walking is a heel strike activity, so I usually recommend medium to high drop shoes as a general rule. People with limitation of ankle joint range of motion can benefit from higher drop shoes regardless of running style as the higher heel creates additional available motion artificially. Higher drop running shoes tend to transfer the strain of running from the foot up the leg to the knees and the hips so those with prior injury to those areas may benefit from lower drop shoes. Conversely, people with plantar fasciitis or Achilles tendonitis can benefit from higher drop shoes due to that upward transfer of strain. Shoe drop is only one of many factors and features to consider when choosing an athletic shoe. If unsure of a choice, it is best to consult with someone experienced in fitting athletic shoes or consider an evaluation from a foot and ankle specialist with experience in sports medicine.