"In your drawings, you will generally have one light source, which determines the location of highlights and the direction of shadows. The spot where the light hits your subject directly is called the highlight, and is usually pure white. The side facing away from the light source will be in shadow. The midtones refer to the gradation of tones between the shadow and the highlight. Most objects will also have an area of reflected light. This reflection happens when light hits the surface next to your object and bounces back. You will notice that these values blend into each other smoothly, which communicates to us the shape of the object. The only time you will see a hard edge is when there is a cast shadow, otherwise the tones change gradually. The closer the cast shadow is to the object, the darker it will be, fading as it moves farther away."