Functional Requirement

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What Does Functional Requirement Mean?

A functional requirement, in software and systems engineering, is a declaration of the intended function of a system and its components. Based on functional requirements, an engineer determines the behavior (output) that a device or software is expected to exhibit in the case of a certain input. A system design is an early form of a functional requirement.

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Techopedia Explains Functional Requirement

Functional requirements of a system can relate to hardware, software or both in terms of calculations, technical details, data manipulation and processing or other specific functionality that defines what a system is supposed to accomplish. A functional requirement can be in the form of a document explaining the expected types of outputs when the device (system) is placed in a certain kind of environment. A functional requirement is said to be a later form of a system design because a design is the outcome of overcoming a certain kind of a problem (technical/non-technical) being faced.

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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.