A set of standard clothing worn by members of an organisation whilst participating in that organisation's activity.
People performing religious activities have often worn standard costumes since the dawn of recorded history. Other early examples of uniforms include the clothing of the armies of the Roman Empire and other civilizations.
One purpose of military uniforms is to clearly distinguish combatants who are protected by the laws of war from other persons carrying weapons, who enjoy no such protection. Another purpose in historical times was to make it difficult for deserterss to avoid detection; military uniforms were so distinctive with many metal buttons and unique colors that they could not be modified into unrecognizable clothing.