A Heel Counter is the part of a running shoe that is frequently added in an attempt to bind the heel of the foot to the shoe. The Science of Running Shoes indicates that this approach is futile, but I'd suggest that a little common sense shows how ridiculous this idea is. Just consider the forces involved when your foot is in contact with the ground and how much pressure a Heel Counter would have to apply to the side of your heel to affect its motion. Thankfully, Heel Counters are generally a harmless waste of effort, though they do needlessly increase the weight of the shoe. Occasionally a shoe will have a Heel Counter that can dig in a little, but that's fairly rare in my experience. Heel Counters can vary from the hard plastic insert shown below, down to a tiny tab of additional fabric that simply prevents the shoe flopping around when it's sitting on the shelf.