Identify a distinguishing feature of draft beer.

Draft beer is characterized by its method of serving, specifically that it is served from kegs using a tap system. This distinctive feature allows for the beer to be dispensed directly from the keg, which helps maintain optimal freshness and flavor. The keg system is designed to keep the beer pressurized, which preserves its carbonation and allows for a smooth pour. This method also facilitates larger quantities of beer to be served at once, making it a popular choice in bars and restaurants.

In contrast, serving beer only in bottles, pouring from a can, or always serving it warm does not accurately describe draft beer. Bottled and canned beers represent different packaging methods that do not involve kegs or taps, while draft beer is typically served chilled to enhance drinkability and flavor.