A shoehorn is a tool with a short handle that flares into a longer spoon-like head meant to be held against the inside back of a snug-fitting shoe so that a person can slide the heel easily along its basin to the inner sole.
 
One of the primary reasons for using a shoe horn is to protect the back of your shoes from damage. When you force your foot into a shoe without a shoe horn, you risk crushing the heel counter, causing creases or even permanent damage to the shoe's structure. This is especially important for leather shoes, where maintaining the shape and integrity is crucial for longevity.