Ankle boots are any styling of boot where the shaft of the boot ends at the ankle line on the wearer. Ankle boots shaft height will typically measure up to 4 1/2".
About Back Zipper:
A back zipper is a slide fastener located at the rear of a garment or shoe. In footwear, a back zipper closure is mostly used in high top boots for women and is intended for esthetic purpose rather than functional.