A hypotrochoid is a type of curve traced by a point attached to a smaller circle that rolls inside a larger stationary circle. The path created depends on the radius of both circles and the position of the tracing point. Hypotrochoids are often used in mathematics and engineering to model complex shapes and patterns. These curves can be visualized using a simple drawing tool called a spirograph, which creates intricate designs by rolling one circle inside another. Hypotrochoids are also related to epitrochoids, which are traced by a point on a circle rolling outside another circle.