A keg coupler is a device used to connect a keg of beer or other beverages to a dispensing system. It allows for the flow of liquid from the keg to the tap, enabling the beverage to be served. Keg couplers come in various types, each designed for specific keg styles, such as D-system for most American beers or S-system for certain European brands. The coupler works by puncturing the keg's seal and creating a pathway for gas and liquid. When the coupler is engaged, it allows carbon dioxide or nitrogen to push the beverage out of the keg and into a glass or cup. Proper use of a keg coupler ensures efficient dispensing and maintains the quality of the beverage.