The main function of a stair skirt board is to protect the walls along your staircase from damage. The part of the wall next to your steps is particularly vulnerable to scuffing as you go up and down your steps. Stair skirt board trim runs along the side of the staircase against the wall and acts as a barrier to prevent the plaster from being accidentally cracked or broken. Skirt board can also offer a more finished look and a higher-end appearance for your stairway.
No matter what style or color your steps are, white tends to be the most common color for stair skirt boards because of how easily it can blend into the wall. However, stair skirting in the same material and finish as your steps can also produce a clean and cohesive look. Here are some examples from other homeowners to help you decide if skirt board stairs are needed in your home.