In engineering, a requirement is a singular documented physical and functional need that a particular product or service must be or perform. It is most commonly used in a formal sense in systems engineering, software engineering, or enterprise engineering. It is a statement that identifies a necessary attribute, capability, characteristic, or quality of a system for it to have value and utility to a user.

In the classical engineering approach, sets of requirements are used as inputs into the design stages of product development. Requirements are also an important input into the verification process, since tests should trace back to specific requirements. Requirements show what elements and functions are necessary for the particular project. This is reflected in the waterfall model of the software life-cycle. However, when iterative methods of software development or agile methods are used, the system requirements are incrementally developed in parallel with design and implementation.

Requirements engineering is the set of activities that lead to the derivation of the system or software requirements. Requirements engineering may involve a feasibility study, or a conceptual analysis phase of the project and requirements elicitation (gathering, understanding, reviewing, and articulating the needs of the stakeholders) and requirements analysis, analysis (checking for consistency and completeness), specification (documenting the requirements) and validation (making sure the specified requirements are correct).

Read more about Requirement:  Origins of Term, Product Versus Process Requirements, Requirements in Systems and Software Engineering

Other articles related to "requirement, requirements":

Behavior Trees - Key Concepts - Requirements Integration
... Once the set of requirements are formalized as individual requirement behavior trees, two joint properties of systems and requirements need to be exploited in order to proceed with composing the ... If the requirement is really part of the system then some other requirement in the set must establish the precondition needed in (1) ... For requirements represented as behavior trees this amounts to finding where the root node of one tree occurs in some other behavior tree and integrating ...
Clearing Balance Requirement
... Financial institutions use the clearing balance requirement (or settlement balances requirement) to describe the amount of money or balance which they anticipate will be required to perform their clearing services ... Manual states "...A depository institution with a reserve balance requirement that has an account at a Reserve Bank may wish to hold balances above its requirement ... institution to establish a clearing balance requirement." ...
Issues - Disputes Regarding The Necessity of Rigour in Software Requirements
... methodologies question the need for rigorously describing software requirements upfront, which they consider a moving target ... Instead, extreme programming for example describes requirements informally using user stories (short summaries fitting on an index card explaining one aspect of what the system should do), and ... Agile methodologies also typically capture requirements in a series of automated acceptance tests ...
Shape Context - Details of Implementation - Step 5: Modeling Transformation - Regularized TPS
... The TPS formulation above has exact matching requirement for the pairs of points on the two shapes ... For noisy data, it is best to relax this exact requirement ... to and for it would be the y-coordinate, ), relaxing the requirement amounts to minimizing where is the bending energy and is called the regularization parameter ...
SS Class Blimp - Requirement
... The situation had become critical and the Admiralty recognised that airships would be effective at spotting submarines and useful for Fleet observations, but at that time Britain's airship fleet consisted of just seven craft – four RNAS airships (HMA 17,18,19, and 20), two continental ships and a small Willows training craft – with only four airfields existing that possessed hangars capable of housing them ... Consequently, on 28 February the First Sea Lord, Admiral Lord Fisher called a meeting with Commander E A D Masterman (Officer Commanding the Naval Airship Section) and representatives from Vickers and the London-based firm of Airships Limited to discuss the possibilities of creating a fleet of suitable patrol airships, sometimes referred to as "scouts" ...

Famous quotes containing the word requirement:

    Reporters for tabloid newspapers beat a path to the park entrance each summer when the national convention of nudists is held, but the cult’s requirement that visitors disrobe is an obstacle to complete coverage of nudist news. Local residents interested in the nudist movement but as yet unwilling to affiliate make observations from rowboats in Great Egg Harbor River.
    —For the State of New Jersey, U.S. public relief program (1935-1943)

    The work of the political activist inevitably involves a certain tension between the requirement that positions be taken on current issues as they arise and the desire that one’s contributions will somehow survive the ravages of time.
    Angela Davis (b. 1944)

    The first requirement of politics is not intellect or stamina but patience. Politics is a very long run game and the tortoise will usually beat the hare.
    John Major (b. 1943)