Slingbacks are a type in shoe in which the heel is exposed yet is contained or secured by a strap that sits above the heel around the ankle.
About Wedge:
Wedge shoes, also referred to as wedge heels or wedges, are shoes with a triangular shape heel in the form of a wedge, with the heel and sole forming a solid block. Wedge heel shoes generally raise the heel of wearer between 1" to 3" and considered to be more stable that other types of high heel shoes. Wedge shoes come in a variety of styles, including sandals, pumps, and boots.