Treads are the flat, horizontal surfaces of a staircase that people step on as they ascend or descend. They are the part of the staircase where your foot makes contact. Treads are essential for providing a safe and comfortable walking surface on stairs.Risers are the vertical components between each tread on a staircase. They form the face of the step, connecting one tread to the next. Risers help prevent you from tripping between steps and add structural support to the staircase.