This article was originally taken from: http://en.wikipedia.org/wiki/Hakama
Hakama (袴) are a type of traditional Japanese clothing. Hakama cover the lower body and resemble a wide, pleated skirt. Hakama were originally worn only by men, but today they are worn (albeit slightly differently) by both men and women. Ladies especially use hakama for graduation, and martial art. It is not normally used along with their kimono. Hakama are tied at the waist and fall approximately to the ankles.
There are two types of hakama, divided (umanori 馬乗り, horse-riding hakama) and undivided (gyōtō hakama 行灯袴). The umanori type are divided like trousers, but nearer the bottom of the garment. This type of hakama are often called “divided skirts”. Both types are identical in outside appearance. A third type, called “mountain” or “field” hakama, were traditionally worn by field or forest workers. They are looser in the waist and narrower in the leg.
Hakama are worn over a kimono. There are four straps, a long one on either side of the front of the garment, and a short one on either side of the rear. The rear of the garment has a rigid board-like section and a toggle which is tucked into the rear of the obi, and helps to keep the hakama in place.
Hakama were originally worn by samurai, and had the same function as chaps, the leather trouser protectors worn by cowboys in the west, that is, to protect the clothing.
Hakama have seven deep pleats, two on the back and five on the front. The pleats are supposed to represent the virtues considered essential by the samurai. Many martial artists continue this tradition, but different sources give different meaning to these pleats.
Men’s hakama The most formal type of hakama are made of stiff, striped silk, usually black and white, or black and grey. These are worn with black montsuki kimono (kimono with one, three, or five family crests on the back, chest, and shoulders), white tabi (divided-toe socks), white under-kimono and woven straw sandals of various types. In colder weather a montsuki haori (long jacket) with a white haori-himo (haori-fastener) completes the outfit.
Hakama can be worn with any type of kimono except yukata (light cotton summer kimono generally worn for relaxing, for sleeping, or at festivals or summer outings). While striped hakama are usually worn with formal kimono, stripes in colours other than black, grey and white may be worn with less formal wear. Solid and gradated colours are also common. A hakama makes any outfit a little more formal.
While hakama used to be a required part of men’s wear, nowadays men usually wear hakama only on extremely formal occasions, and at tea ceremonies, weddings, and funerals. Hakama are also regularly worn by practitioners of a variety of martial arts, such as kendo, aikido, kyudo, et cetera. It is said that the flowing fabric of the hakama can disguise the movements of the warrior giving him an advantage in combat.
Hakama in tea
In tea the hakama is only slightly divided, making riding or fighting in it impossible.
In tea menn will almost always use a hakama. After recieving Chamei and Monkyo one are premitted to wear a Jittoku instead of hakama. So than one can chose to either use the hakama or the jittoku, but any way one of them is still almost always required. This is ofcourse not true for keiko only events and tea gatherings.