In the lexicon of United States militaria, badges worn by members of the armed forces are similar to those worn by police officers or firefighters. Like civilian-service badges, military badges encompass insignia awarded to convey rank, as well as qualifications for various skills—from "wings" in the Air Force for pilots to "diver" badges in the Army, Navy, Coast Guard, and Marines to signify a person qualified for underwater operations.
To serious military medal collectors, though, the word “badge” can be parsed even more precisely. For them, “badge” is the word given to Orders (governmental acknowledgements of acts performed by citizens, civilian or military, occurring during a war or not) that are meant to hang from a ribbon. That’s different from a decoration, which can also be a medal and can also hang from a ribbon, but is only awarded for acts performed by military personnel during combat.
This distinction seems simple enough, but many militaria collectors find themselves reverting to the sheriff/firefighter association of the word when talking about badges, using the term to describe just about any metal insignia that is pinned to a uniform rather than hung from a ribbon.
Some of the easiest military badges to identify without fear of contradiction are those worn by military police, or MPs. Often made of stamped brass, these shield-shaped badges have all the usual elements and devices seen on regular police badges—an eagle at the top, a liberty cap hoisted on a pole, an American flag.
Other badges are smaller, resembling what most people might call a pin, and meant to be worn on either a jacket or cap. These badges frequently do little more than signify one’s skill as, say, a welder or surgeon. Other small badges note one’s ability to jump out of airplanes (a parachutist’s badge) or play the trumpet (as seen in a badge for a company’s bugler).