Upholstery is the materials—which include fabric, padding, webbing, and springs—that make up the soft coverings of chairs, sofas, and other furniture. The process began in the Middle Ages and grew in popularity during the 17th, 18th, and 19th centuries. Over the years, a wide variety of materials have been used, from hay to horsehair to wool. Modern upholstered items use metal springs and foam for greater durability. While the interior materials may not be visible, they make a big difference in whether the piece is comfortable . And though fabric can always be changed—and may need to be, depending on wear and tear—choosing high-quality inner layers will help make sure the piece will last for years to come.