Crinolines are structured undergarments worn beneath skirts to create a fuller shape. They were popular in the mid-19th century, particularly during the Victorian era, and were made from materials like horsehair, cotton, or steel. Crinolines helped women achieve the fashionable silhouette of the time, which emphasized a narrow waist and a wide skirt. The design of crinolines evolved over the years, leading to variations such as the hoop skirt and the petticoat. While they provided volume, crinolines could also be cumbersome and restrictive. Today, they are often associated with historical costumes and formal wear, reflecting the fashion trends of their time.