A lapel pin is, wait for it, a pin that is most commonly worn on a jacket lapel. They can either be small badges that indicate someone's affiliation to a group or cause - such as Lapel Pin University
Pins can be ornamental and simply used to jazz up a simple outfit. However, they can also send a message about the wearer. Some may want to show off their political affiliations, while others may simply want to mix things up and have some fun. I love wearing USA Custom Lapel Pins https://www.pinsource.com/custom-lapel-pins/made-usa on my denim jacket. This looks cool!