User story vs. Functional Requirement Documents

In my experience so far, I have observed many Business Analysts getting confused between user stories in agile scrum and functional requirement documents in waterfall methodology. It is important for a BA to be 100%. clear on differences between these two so that they can be accurate and effective while writing any of them.

A user story is a concise description of a desired feature or functionality from the perspective of an end user or customer. It captures the "who," "what," and "why" of a particular requirement along with related acceptance criteria.

User stories are supposed to be written in a non-technical language and focus on the user's needs and expectations.

User stories follow a specific template, often known as the INVEST criteria:

• Independent: Each user story should be self-contained and independent from other stories.
• Negotiable: User stories are open to discussion and can be refined and modified during the development process.
• Valuable: User stories must provide value to the end user or customer.
• Estimable: User stories should be relatively easy to estimate in terms of development effort.
• Small: User stories should be small enough to be completed within a single sprint.
• Testable: User stories should have clear acceptance criteria that define when the story is considered complete.

PS: The above explanation is a universal understanding of User stories, not my original thought.

On the other hand, functional requirement documents in waterfall methodology are detailed specifications that describe what the system should do, often in a more technical and precise manner. The requirements are typically documented early in the software development lifecycle and form the basis for the entire project.

Functional requirement documents are often comprehensive and may include detailed descriptions of input/output formats, processing logic, error handling, user interfaces, and other technical aspects of the system. They are usually created before the development work begins and serve as a blueprint for the entire project.

Unlike user stories in agile, functional requirement documents in waterfall methodology focus more on the technical implementation details and less on the end user's perspective. They aim to provide a complete and detailed understanding of what the system should deliver without much room for flexibility or iterative refinement during the development process.

It's important to note that these methodologies have different approaches to software development, and the way requirements are documented and managed reflects those differences. Agile Scrum emphasizes flexibility, collaboration, and incremental development, while waterfall methodology follows a more sequential and rigid approach.

Hope that this gives clear idea on key differences. Every methodology has its pros & cons. Please do utilise what works best for your project, customer and organisation.