This document provides information about different types of doors and windows. It defines threshold as the bottom of a doorway, and lists different materials used for thresholds like wood and marble. It also describes surface sliding doors, folding or bi-fold doors, louvered doors, and metal door frames. Additionally, it defines muntins and mullions as divisions in windows, and transom windows as windows above doors. Finally, it provides details about Palladian windows, noting they have a larger central arched section between two smaller side sections and were popular in Renaissance and classical architecture.