A corset is a support garment worn to hold and train the torso into the desired shape and posture. They are traditionally constructed out of fabric with boning made of whalebone or steel, a stiff panel in the front called a busk which holds the torso rigidly upright, and some form of lacing which allows the garment to be tightened. Corsets were an essential undergarment in European women's fashion from the 17th century to the early 20th century. In the 17th and 18th centuries they were commonly known as "stays" and had a more conical shape. This later evolved into the curvaceous 19th century form which is commonly associated with the corset today. By the beginning of the 20th century, shifting gender roles and the onsets of World War I and II (and the associated material shortages) led the corset to be largely discarded by mainstream fashion.
Since the corset fell out of use, the fashion industry has used the term "corset" to refer to undergarments or shirts which, to varying degrees, mimic the look of traditional corsets. While these modern corsets and corset tops often feature lacing or boning, and generally imitate a historical style of corsets, they by-and-large have very little, if any, effect on the shape of the wearer's body. Elasticated garments such as girdles and waist trainers are still worn today and serve to compress the waist or hips, although they lack the rigidity of corsets. A corset brace is a type of orthotic resembling a traditional corset, used to support the lower back in patients with mild to moderate back pain.