The term 'Parts of a Stair' refers to the components that make up a staircase. The most common parts are the steps, which are the individual pieces of material that form the treads and risers of the stairway. Other parts include the handrails, balusters, newels, and stringers. The handrails are the horizontal bars that provide support when ascending or descending the stairs. Balusters are the vertical posts that provide support for the handrails. Newels are the larger posts at the top and bottom of the stairway that provide additional support. Finally, the stringers are the structural members that support the steps. All of these parts work together to create a safe and functional staircase.