What is the term for the horizontal portion of a stair system that connects each riser?

The correct term for the horizontal portion of a stair system that connects each riser is the tread. Treads are the flat surfaces of the steps where a person places their foot when ascending or descending a staircase. They are critical for safety and usability, as the width and depth of the tread directly impact how easy and comfortable it is to use the stairs.

In carpentry, understanding the functions of various components of a stair system is essential. Treads need to be designed to be deep enough to provide a secure footing while being wide enough to accommodate different foot sizes. They are often made from durable materials to withstand wear and tear over time.

In the context of the other options, risers are the vertical components that connect each tread, stringers are the structural elements that support the treads and risers, and landings are flat surfaces at the top or bottom of the stairs or where the direction of the staircase changes. While all these elements play integral roles in a stair system, it is the tread that specifically refers to the horizontal part where feet are placed during use.