A border guard of a country is a national security agency that performs border control, i.e., enforces the security of the country's national borders. Some of the national border guard agencies also perform coast guard (as in Germany or Ukraine) and rescue service duties.
In different countries, names of particular border guard services vary significantly. The service may be called "police", "guard", "troops" or "sentinel" and the name would refer to the nation's official term for the state border - whether it is "frontier" or "border".
Most border guards of the world use dark green-colored elements on their uniform, insignia or flags.
During peacetime special border patrolling forces, the Border guard, mans the chain of Border Outposts which are maintained all along international borders by countries to check smuggling, infiltration by spies of untrusted neighboring countries, insurgents bent on smuggling weapons and explosives for terrorist attacks and subversive activities, illegal immigration and human trafficking etc. Patrols go out regularly from the Border outposts to patrol the international border to check illegal crossings and track any footprints of those who may have crossed over illegally or attempted to. In case intrusion by foreign elements is confirmed, it is the responsibility of the Border guard based on the post to trace the intruders by checking the nearby settlements, villages and towns and inform the law enforcement agencies, Customs and Police authorities.
Typical tasks of a Border Guard are:
The Border Guard may also perform delegated customs and immigration control duties.
During wartime however the Border guard withdraw from the Border outposts and provide assistance in a limited capacity to the country's regular army which then comes and mans all the border outposts at the international border facing the enemy neighboring country. Wartime assistance of the Border guard to the Army is essential as they are familiar with the local terrain having patrolled it on a daily basis during peacetime. During wars, Border outposts are reworked into well fortified dug-in positions from where regular Army units can operate to defend the territorial integrity of the country.