Final answer:
Vietnamese coffee is predominantly made with the Robusta coffee bean, a variety that is stronger and more bitter than the globally recognized Arabica bean.
Step-by-step explanation:
The type of coffee bean commonly used to make Vietnamese coffee is the Robusta bean. This variety is distinct from the Arabica bean, which is perhaps the most globally recognizable coffee bean, originating from the Horn of Africa and popularized through Yemen's historical trade.
While Coffea Arabica is known for its smooth and flavorful profile, Vietnamese coffee typically uses the stronger and more bitter Robusta variety, which thrives in the country's climate and has a higher caffeine content. Vietnamese coffee is traditionally made using a special drip filter called a 'phin', and is often served with sweetened condensed milk to offset the Robusta's intense flavor.