The end-user is a popular concept in software engineering, referring to an abstraction of the group of persons who will ultimately operate a piece of software (i.e. the expected user or target-user). This abstraction is meant to be useful in the process of designing the user interface, and is therefore built on a relevant subset of any user's characteristics which may include which computer interfaces he/she is comfortable with (having used them before or because of their inherent simplicity), his/her technical expertise and degree of knowledge in specific fields or disciplines, and any other information which is believed to be relevant in a specific project.