User requirements are the needs and expectations of the people who will use a product, system, or service. They are essential for engineering design, as they guide the design decisions and ensure that the final outcome meets the user value proposition and requirements. In this article, you will learn about the different types of user requirements and how to elicit, analyze, and document them.
Functional requirements specify what the product, system, or service should do or provide. They describe the features, functions, behaviors, and inputs and outputs that the user expects or requires. For example, a functional requirement for a smartphone app could be: "The app should allow the user to create, edit, and delete notes." Functional requirements are usually expressed in terms of verbs, actions, or outcomes.
Here are the three most common ways to generate functional requirements: 1. Stakeholder Input: Gather input from stakeholders, including end-users, clients, and experts, through interviews and workshops. 2. Use Case Analysis: Create use cases to identify requirements by focusing on user perspectives and system interactions. 3. Best Practices & Benchmarking: Research industry standards and successful systems to inform functional requirements. These methods help ensure that functional requirements are comprehensive, well-defined, and aligned with user needs and industry standards.
Non-functional requirements specify how the product, system, or service should perform or operate. They describe the quality, reliability, usability, security, efficiency, and maintainability of the product, system, or service. For example, a non-functional requirement for a smartphone app could be: "The app should load within 3 seconds and have a user-friendly interface." Non-functional requirements are usually expressed in terms of adjectives, criteria, or standards.
User interface requirements specify how the product, system, or service should look and feel to the user. They describe the layout, design, appearance, and interaction of the user interface elements, such as buttons, menus, icons, colors, fonts, and feedback. For example, a user interface requirement for a smartphone app could be: "The app should have a dark mode option and use intuitive icons and gestures." User interface requirements are usually expressed in terms of visual, aesthetic, or ergonomic aspects.
User experience requirements specify how the product, system, or service should affect the user's emotions, attitudes, and satisfaction. They describe the benefits, values, goals, and expectations that the user seeks or desires from the product, system, or service. For example, a user experience requirement for a smartphone app could be: "The app should make the user feel productive and organized." User experience requirements are usually expressed in terms of emotions, motivations, or outcomes.
Business requirements specify what the product, system, or service should achieve or deliver for the organization or stakeholder that develops or provides it. They describe the objectives, strategies, constraints, and metrics that the product, system, or service should align with or support. For example, a business requirement for a smartphone app could be: "The app should generate revenue from in-app purchases and advertisements." Business requirements are usually expressed in terms of numbers, values, or targets.
Regulatory requirements specify what the product, system, or service should comply with or adhere to in terms of laws, regulations, standards, or policies. They describe the rules, obligations, or responsibilities that the product, system, or service should follow or fulfill. For example, a regulatory requirement for a smartphone app could be: "The app should respect the user's privacy and data protection rights." Regulatory requirements are usually expressed in terms of norms, codes, or principles.
Understanding your requirements means you understand the system and the customer! Understanding requirements in systems engineering is vital for clear system design, aligning with user needs, and early issue identification, reducing costly changes. It streamlines efficiency, optimizes resources, and establishes quality standards. Meeting requirements ensures stakeholder satisfaction and aids system documentation and maintenance for future improvements.