What is "insteps"

Usage examples of "insteps".

She bought sandals too with pearl tassels on the insteps, and held a dress rehearsal that evening, and Wilkes, who was rather good with hair, made a complicated pile of curls on top of her head, while several friends offered a variety of evening wraps.

Thomas buckled the straps that fit under the Wellingtons insteps tight to ensure unwrinkled perfection over his muscular thighs.