Pleats are not to be confused with creased pants. Creased pants feature a crease that extends down the leg. Pleats are created when the fabric is folded over on itself and sewed in place.
Salwar pleaded pants have been worn in India for over 2,000 years. Another pleated style called Gurkha trousers were worn by the military in Nepal. Nineteenth century British military styles adapted the comfortable trousers. Gurkha pants are double pleated in front and feature a high waistband fastened with a buckle.
Pleated pants were popular in Western men's suits in the 1930s and became the go to style in the late 1940s and 1950s. After disappearing in the 1960s, they regained popularity in the 1990s.