There are 3 types of coffee used in espresso machines.
Ground coffee is one of the most common coffees used in espresso machines. Different methods are employed to produce ground coffee. The most common of these is the crushing of the beans into a powdery substance. This forms part of the ritualistic joy for some of the espresso drinking experience. One disadvantage of ground coffee is it is messier to use than other types of coffee, forcing a user to constantly clean the machine. On the plus side extracted grounds can be disposed of in an environmentally friendly way by composting the coffee waste in a standard compost heap. The best type of ground coffee to use with an espresso machine is a blend of Arabica beans, as espresso machines do do not tend to work as well with the purer blends.
Coffee beans have the advantage of tasting fresher than ground coffee. In order to capture coffee beans in the best possible condition you should invest in a bean to cup machine that comes ready made with a built in grinder. This type of machine will instantly grind the beans for you, allowing them to be quickly ready for brewing. This bean to cup device allows you to cut down on mess as it removes the need for an individual to be involved in the tamping process. In addition, coffee beans provides, in my opinion, the best possible flavour of any coffee. The main disadvantages to bean to cup machines are the fact that the grinder can be noisy and they can also cost more than machines that produce ground coffee. If you feel the bean to cup grinder is not within your budget, you can always invest in grinders which are sold as standalone devices.
Coffee capsules are entirely different from ground and roast coffee in that they come supplied in sealed containers that are inserted into the espresso machine. Once they are inserted their outer casing is pierced and the coffee inside fills with hot water. From this point on the coffee is automatically discharged into your cup. The advantages of coffee capsules are they have a long shelf life – lasting in some cases up to 9 months – and they do not create the same mess as ground coffee. The disadvantages are you do lose some flexibility as the capsules can only be used with specific machines. They also tend to work out slightly more expensive per shot than ground coffee. In the international context, Nepresso are one of the largest manufactures of these types of machines.