It includes oral nutritional supplements (ONS) as well as tube feeding via nasogastric, nasoenteral or percutaneous tubes. This definition differs from definitions used in many other publications where ‘‘EN’’ is rather used for tube feeding only regardless if blenderized food or specific industrial products are used. This decision was based on the fact that many studies dealing with EN report on both ONS and tube feeding. Furthermore, prescription and reimbursement of EN is in many countries dependent of the use of industrial products rather than the route of application. EN is part of a qualified nutritional regimen in the in- and outpatient setting, and usually one of the tasks of professionals with special training in EN or the nutritional support team.