requirement

A requirement is a stated or implied need, expectation, or condition that must be fulfilled by a product, process, system, or organization. In industrial and regulated environments, requirements provide the formal basis for design, operation, verification, and audit of manufacturing and quality systems.

Scope and types of requirements

In manufacturing and operations, the term commonly includes:

• Customer requirements: Specifications, drawings, contracts, and service expectations defined by external or internal customers.
• Regulatory and statutory requirements: Laws, regulations, and official rules that apply to products, processes, facilities, data, and records.
• Standards and internal policies: Company procedures, work instructions, engineering standards, and quality system rules.
• Technical and interface requirements: Functional, performance, safety, cybersecurity, interoperability, and integration needs across OT and IT systems.
• Process and quality requirements: Tolerances, control limits, inspection criteria, data recording rules, and traceability expectations.

Requirements may be explicitly documented or implied by customary practice, contracts, or applicable regulations. For operational control and audits, organizations typically treat requirements as documented, version-controlled items.

Operational use in industrial and quality systems

Requirements appear across the lifecycle of manufacturing systems and products, including:

• Requirements definition and capture: Gathering and formalizing needs from customers, standards, regulations, and internal stakeholders.
• Requirements management: Organizing, reviewing, approving, baselining, and version-controlling requirements, often in dedicated tools or within PLM, MES, or ERP-connected systems.
• Requirements allocation: Decomposing and assigning high-level requirements to subsystems, processes, equipment, software, and suppliers.
• Requirements traceability: Linking requirements to designs, risk assessments, control plans, work instructions, test methods, validation protocols, and production records.
• Requirements verification and validation: Demonstrating that each requirement is implemented correctly and that the overall solution meets intended use, often using tests, inspections, simulations, or process capability studies.
• Change control: Assessing and controlling changes to requirements, including impact on design, qualification, production, documentation, and training.

In regulated contexts, clarity about which requirements apply, where they are documented, and how they are met is central to audits and investigations.

Relationship to ISO 9000 concepts

In quality management, the term commonly refers to a need or expectation that is stated, generally implied, or obligatory. Within a quality management system, this spans customer contract clauses, regulatory rules, internal procedures, and technical specifications that an organization must consider and control. Making requirements explicit, assigning ownership, and maintaining evidence of conformity are key parts of quality and compliance workflows.

What a requirement is not

• It is not the same as a task; a task is an activity, while a requirement is a condition or expectation that tasks help satisfy.
• It is not just a goal or aspiration; a requirement is something that must be fulfilled under defined conditions.
• It is not automatically a design solution; it describes what is needed, not necessarily how to implement it.

Common confusion

• Specification vs requirement: A specification is usually a detailed document that contains many requirements and supporting information such as rationale, background, or examples. A requirement is a single need or condition, often expressed as an atomic statement.
• User story vs requirement: In software or MES development, user stories describe desired behavior from a user perspective, while requirements may be more formal, structured, and testable statements that can trace directly to verification evidence.
• Regulation vs requirement: Regulations are external rules set by authorities. Specific requirements are how an organization interprets and implements those rules within its processes, systems, and documentation.