A military uniform is a standardized outfit worn by members of the armed forces and paramilitary groups across various nations. Over the centuries, military dress has seen substantial evolution, transitioning from colorful and ornate attire in the 19th century to practical camouflage uniforms used for combat beginning in World War I (19141918). These uniforms serve as standardized and distinctive attire for identification and display, symbolizing organized military forces supported by a central authority. Military uniforms vary not only between military units but also in formality levels according to Western dress codes: full dress for formal occasions, mess dress for evening events, service dress for casual settings, and combat uniforms, which are akin to casual wear. Physical training uniforms may also be included in the casual category. The field dedicated to designing and producing military uniforms is known as military textile science.