An edge case is a problem or situation that occurs only at an extreme (maximum or minimum) operating parameter.
For example, a stereo speaker might distort audio when played at its maximum rated volume, even in the absence of other extreme settings or conditions.
An edge case can be expected or unexpected. In engineering, the process of planning for and gracefully addressing edge cases can be a significant task, and one that may be overlooked or underestimated. Engineering is the Discipline and Profession of applying technical and scientific Knowledge and Non-trivial edge cases can result in a failure of the object being engineered that may not have been imagined during the design phase or anticipated as possible during normal use. Design is used both as a Noun and a Verb. The term is often tied to the various Applied arts and Engineering (See design disciplines For this reason, attempts to formalize good engineering practices often incorporate information about dealing with edge cases.