Men may wear shorts as custom

Shorts are a garment worn by both men and women over their pelvic area, circling the waist and splitting to cover the upper part of the legs, sometimes extending down to the knees but not covering the entire length of the leg. They are called "shorts" because they are a shortened version of trousers, which cover the entire leg. Shorts are typically worn in warm weather or in an environment where comfort and air flow are more important than the protection of the legs.

There are a variety of shorts, ranging from knee-length short trousers that can in some situations be worn as formal clothes to beachwear and athletic shorts. Some types of shorts are typically worn by women, such as culottes , which are a divided skirt resembling a pair of loose-cut shorts. 

In the 1890s, knee pants (an early type of short pants) became the standard wear for American boys. Many urban school portraits from the 1890s show all but the oldest boys wearing knee pants. North American boys normally wore knee pants with short stockings. This began to change after the 1900s when North American boys began wearing knickerbockers, while short pants became more popular in Europe. In the 1930s, shorts started to be worn for casual comfort (e.g. outdoor and athletic activities) by both men and women. However, it was still taboo to wear shorts outside certain activities. 

Since about the time of World War two, when many soldiers served in tropical locations, adult men have worn shorts more often, especially in summer weather, but the perception of shorts as being only for young boys took several decades to change, and to some extent still exists in certain circles. By the late 20th century however it became common for men to wear shorts as casual wear in summer.

However, in many countries there are few formal settings where wearing shorts would be acceptable, as they are considered casual wear. Notable exceptions where men may wear short trousers to the office or at a formal gathering are South Africa, Bermuda, Australia and New Zealand. Since the 1990s, casual office dress has grown to include formal shorts in some UK and U.S. businesses, but by no means universally. 
Adults are also commonly seen wearing shorts, however wearing shorts is less common among women in traditional eastern countries than in the West, although this varies widely by region - women more often wear shorts in large, cosmopolitan cities. In some countries adult women can be seen wearing loose-fitting shorts that end at or just below the knee, as these are seen as sufficiently modest.