Service dress uniform is the informal type of uniform used by military, police, fire and other public uniformed services for everyday office, barracks and non-field duty purposes and sometimes for ceremonial occasions. It frequently consists of a jacket, trousers, dress shirt, and neck tie, along with orders, medals, and insignia. Design may depend on regiment or service branch, e.g. army, navy, air force, marines, etc. In Western dress codes, a service dress uniform is a permitted supplementary alternative equivalent to the civilian suit - sometimes collectively called undress or "dress clothes". As such, a service dress uniform is considered less formal than both full dress and mess dress uniforms, but more formal than combat uniforms.

A uniform is a variety of costume worn by members of an organization while usually participating in that organization's activity. Modern uniforms are most often worn by armed forces and paramilitary organizations such as police, emergency services, security guards, in some workplaces and schools and by inmates in prisons. In some countries, some other officials also wear uniforms in their duties; such is the case of the Commissioned Corps of the United States Public Health Service or the French prefects. For some organizations, such as police, it may be illegal for non members to wear the uniform.