police officer
Uniformed person responsible for maintaining law and order.
identification badge 
Symbol indicating a police officer’s name.
shoulder strap 
Decorative tab attached to the shoulder and sometimes buttoned down; it is inspired by the military uniform.
rank insignia 
Symbol indicating a police officer’s rank.
badge 
Symbol indicating the force an officer belongs to as well as the officer’s identification number.
cap 
Brimless, somewhat soft headgear that has a peak and a flat crown.