We've all seen those crisp flat hats and the perfectly ironed pants, not to mention those dress coats that are such a deep blue that they look almost black. The dress uniform of a U.S. Marine is one of the most recognizable military symbols in the world. The men and women who wear them are esteemed as members of one of the most storied and daring fighting forces in the world. But when, where and how is a marine to wear the honored uniform? What regulations dictate its uses? To answer that, one must look to the Permanent Marine Corps Uniform Board. The PMCUB is the organization tasked with choosing the Marine Corps uniform and regularly updating the regulations that dictate all Marine Corps uniforms. PMCUB's manual can be found online.

The Marine Corps dress blues uniforms have four classifications. They are class A, B, C, and D uniforms. Each classification of uniform is authorized for different functions, and all but class "A" uniforms may be designated as "uniform of the day" by the unit commander.

The class "A" uniform is also known as the evening dress uniform. According to the PMCUB, it is "prescribed for official formal evening functions at which civilians would normally wear evening clothes or "white tie" attire. Occasions for the class "A" uniform include state occasions at the White House or foreign embassies

The PMCUB describes the Class B uniforms as consisting of "the same items as blue dress "A" except that ribbons are worn in lieu of medals." The dress B uniform may be prescribed for parades, informal social gatherings or as the uniform of the day.

The Marine Corps Class "C" uniform is a bit less formal than the class "B." The class "C" may also be prescribed by the commander for parades and other ceremonies. The class "C" may also be worn on leave or liberty. The class "C" consists of all the components of the Class "B" except for the blue dress coat. The class "C" is comprised of the long sleeve khaki shirt and tie for males or the neck tab for females.

Class "D" uniform is also worn without the dress coat, but it consists of a short sleeve khaki shirt and is not worn with the necktie or neck tab. It is prescribed for honors and ceremonies where the environment would preclude the comfortable wear of the dress "A" or "B" uniforms. It may be worn as the uniform of the day or on leave or liberty.