An open back shoe is a type of footwear that has an open heel and usually a strap or buckle across the top of the foot. The term 'SLING' is often used to describe this type of shoe, as it is designed to be worn with the heel open and the strap or buckle providing support. Open back shoes are typically more casual than closed back shoes, and can be found in a variety of styles, from sandals to dress shoes.