A single serve coffee maker is a coffeemaker that can be used to brew a single cup of coffee. The concept of single serve is usually related to automatic drip coffee brewers, since the classic automatic drip coffee machine cannot make small quantities of coffee. Although espresso machines brew a single serve, they are not included in the category. The same with manual coffee brewers.
The advantage of brewing a single cup is the that by brewing on demand we always have freshly brewed coffee. Classic automatic drip coffee makers can only brew larger quantities of coffee. Single cup coffee machines can use loose ground coffee, or coffee capsules. The capsule based systems are more convenient, and they offer consistency.