Airline pins are pins used by the airlines to distinguish between personnel with different levels of training.  They are sold on the internet by various companies.  They are also sold as souvenirs by the airlines.  The airline pins sold by the airlines are subtly different from the ones they give out to their employees, and are meant to be placed differently.  

Airline pins given to employees are meant to be worn as part of the uniform provided by the airline, and are attached to the lapel, shoulder pads, and cuffs of the uniform.  The airline pins sold to the public can of course be attached to the same places, or they can be attached to things such as a piece of luggage.  These airline pins can also be attached to magnets which can in turn be placed on any metallic surface as a reminder of the trip or possibly as a reminder of the job (as in a retirement badge).

Airline pins are extremely inventive.  There are pins commemorating every different airplane that ever existed.  I saw pins commemorating the 727, the 737, the 737-800, the 747, and the 777.  All these planes were made and flown by Boeing. 

There are also airline pins made to celebrate aviation companies like Boeing, with company logo pins being displayed for many airlines.  I found an Air Canada pin alongside an Air Wisconsin pin.  There was an Air France pin on display, as was an All Nippon Airways pin.  I found an American Airways pin from the 1950's, and another one from the 1960's.  America Air Trans and the Bonanza airlines no longer exist, but I found pins celebrating their companies.  

I found many airline pins from companies that I didn't even recognize, like the Compass air pin, which actually had a tiny compass built into the pin.  The Frontier Airlines pin looked like something made up by a forest ranger or a group of Boy scouts, while the Hawaii Airlines pin featured a lei and a volcano.  National Airlines had a pin dating from the 1950's which had a duck on it.  The same type of duck was also found on the North Central pin, which dated from the 1970's.  Northwest had  an arrowhead on their 1940's pin, and there were many airline pins which had a picture of the tail end of an airplane on them .  I suppose the imagery was supposed to convey an impression of speed, as if the airplane was going so fast that the tail was all you could see.