Rượu mạnh refers to high-proof alcoholic spirits, typically distilled to an alcohol content of 40% ABV or higher. Common examples include whisky, vodka, rum, gin, brandy, and cognac, as well as traditional Vietnamese spirits like rượu đế. These liquors are produced through fermentation and distillation processes that concentrate ethanol, resulting in a potent beverage often consumed neat, on the rocks, or used as a base in cocktails.