True need-

A design exists solely in response to a specified or a perceived need and, therefore, the satisfaction of that need is the most essential function of a design. However, this is not as simple as it appears. Very, often the statement of need that a designer starts her work with, is incomplete or even misleading. One of the most difficult problems faced by a designer is to isolate the ‘true’ need of a given situation from all the various expressions of need that she may be given.

Need-

A design exists solely in response to a satisfied or a perceived need and, therefore the satisfaction of that need is the most essential function of a design