Agile Requirements Foundations

Agile Requirements Foundations is the set of concepts describing what a requirement is within an agile context and how agile approaches treat the discovery, detailing, and change of requirements differently than a traditional, fully-specified-upfront approach would. Where backlog items represent individual pieces of work in an ordered list, requirements describe the underlying statements of need that give those items their substance, and agile requirements foundations addresses how those statements of need are understood, expressed, and allowed to evolve.

A central theme running through this foundation is that agile approaches expect requirements to become clearer over time rather than assuming they can be fully and correctly specified before any work begins. This expectation shapes several of the concepts here, including the idea of requirements that emerge only once work is underway, the deliberate acceptance of some ongoing uncertainty, and a preference for adjusting the level of detail applied to a requirement based on how soon it will actually be worked on.

Defining Requirements and Their Types

Agile Requirements Definition

Agile requirements are statements of what a product or project needs to do or provide, treated within agile approaches as subject to ongoing refinement and change rather than fixed in full detail from the outset.

Requirement Definition

A requirement is a specific statement describing a capability, condition, or constraint that a product or project must satisfy, forming the basic unit from which more detailed backlog items and specifications are derived.

Functional Requirement Definition

A functional requirement describes a specific behavior or capability a product must exhibit, expressed in terms of what the system should do in response to a given input or condition.

Nonfunctional Requirement Definition

A nonfunctional requirement describes a quality or constraint the product must satisfy that is not tied to a specific behavior, such as how reliably or how quickly a system must perform its functions.

Requirements That Change and Emerge

Emergent Requirement Definition

An emergent requirement is a requirement that becomes known only as work progresses and understanding deepens, rather than being identifiable in full at the start of a project, reflecting agile's expectation that not everything can or should be specified upfront.

Requirement Uncertainty Definition

Requirement uncertainty is the deliberate acceptance that some requirements remain incompletely understood at a given point in time, treated as a normal condition to be resolved through iterative discovery rather than as a planning failure.

Requirement Change Definition

A requirement change is any modification to a previously stated requirement, expected and accommodated within agile approaches as part of the ongoing refinement of understanding rather than treated as an exception requiring special justification.

Managing Requirement Detail and Quality

Requirement Detail Definition

Requirement detail is the depth of specification applied to a given requirement, typically kept lower for requirements not yet scheduled for near-term work and increased as that work approaches, consistent with backlog granularity.

Requirement Validation Definition

Requirement validation is the process of confirming that a stated requirement actually reflects a genuine need, typically checked through direct stakeholder input rather than assumed correct simply because it was written down.

Requirement Traceability Definition

Requirement traceability is the ability to connect a specific requirement forward to the work items and delivered output that fulfill it, providing a way to confirm that a stated need has actually been addressed by the work done.