They check to see that windows, doors, and gates are locked. They also make sure that security equipment is working correctly. In stores, guards watch for theft by customers. In banks, guards watch for robbers. In offices and factories, guards protect equipment from theft.
Some guards check employee identification and answer visitor questions.
Other guards patrol places of entertainment, such as nightclubs. They protect property and stop trouble from customers. Security guards often monitor electronic security systems and keep in radio contact with other guards. Guards patrol on foot or in a car. Sometimes one guard must perform all the duties.