User Stories vs Use Cases vs Requirements
A BA’s Ultimate Cheat Sheet
🔥Why This Matters.
Ever been in a meeting where “requirements” get tossed around like a magic word?
Then someone throws in “user stories”... and suddenly, “use cases” enter the chat. Now, no one’s sure what they’re even talking about.
If you’re a Business Analyst, this confusion is dangerous.
❌ Get it wrong → Missed expectations, frustrated developers, failed projects.
✅ Get it right → You become the glue that holds the team together.
Let’s clear this up once and for all.
👇 If you want to avoid them, keep reading.
1️⃣ What Are User Stories?
📌 Definition:
User stories are short, simple descriptions of a feature from the end user’s perspective. They focus on what the user wants to achieve—not how the system does it.
📌 Format:
👉 “As a [user], I want [action], so that [outcome].”
📌 Example:
"As a customer, I want to reset my password, so that I can access my account when I forget my credentials.”
📌 When to Use User Stories:
✅ Agile projects (fast-moving, iterative work)
✅ MVPs (prioritizing the most valuable features)
✅ Collaboration (encourages conversation over documentation)
📌 Common Mistakes:
❌ Writing technical stories → “As a system, I want…” (Systems don’t want things!)
❌ Leaving out acceptance criteria → Devs shouldn’t have to guess what "done" looks like.
❌ Making them too big → Break down epics into smaller, manageable stories.
🔥 Pro Tip: Attach acceptance criteria to every user story so there’s no confusion on when it’s done!
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2️⃣ What Are Use Cases?
📌 Definition:
Use cases describe how a user interacts with a system to achieve a goal. They focus on step-by-step workflows and system behavior.
📌 Structure of a Use Case:
🔹 Primary actor → Who is interacting with the system?
🔹 Goal → What is the actor trying to achieve?
🔹 Main flow → The normal step-by-step interaction.
🔹 Alternate flows → What happens if something changes or goes wrong?
📌 Example (Use Case: Resetting a Password):
🔹 Primary Actor: Customer
🔹 Goal: Reset password
🔹 Main Flow:
1️⃣ Customer clicks "Forgot Password”
2️⃣ System asks for email
3️⃣ Customer enters email
4️⃣ System sends reset link
5️⃣ Customer resets password
🔹 Alternate Flow: Invalid email entered → System shows error message
📌 When to Use Use Cases:
✅ Complex workflows with multiple steps
✅ System behavior documentation for developers & QA
✅ Edge case handling (alternate and exception flows)
📌 Common Mistakes:
❌ Overcomplicating → Keep flows clear and focused!
❌ Missing alternate paths → What happens when something goes wrong?
❌ Ignoring user goals → Stay focused on why the user is doing this.
🔥 Pro Tip: Use flowcharts or activity diagrams to visualize use cases—it makes them much easier to understand!
3️⃣ What Are Requirements?
📌 Definition:
Requirements are detailed specifications of what a system must do—and sometimes how it should do it.
📌 Types of Requirements:
✔ Functional Requirements → What the system must do (e.g., “The system must allow password resets”).
✔ Non-functional Requirements → Performance, security, usability (e.g., “The system must send reset emails within 5 seconds”).
📌 Example:
🔹 Functional Requirement: "The system must allow users to reset their password via a secure email link.”
🔹 Non-Functional Requirement: "The reset email must be delivered within 60 seconds of the request.”
📌 When to Use Requirements:
✅ Formal documentation for large-scale projects
✅ Regulatory and compliance-driven projects
✅ Detailed system behavior and performance expectations
📌 Common Mistakes:
❌ Mixing functional and non-functional requirements
❌ Creating endless wishlists without prioritization
❌ Forgetting testability → If you can’t measure it, it’s not a good requirement.
🔥 Pro Tip: Use the INVEST framework for writing strong requirements:
✔ Independent
✔ Negotiable
✔ Valuable
✔ Estimable
✔ Small
✔ Testable
4️⃣ How to Choose the Right Approach
Still unsure? Use this quick guide to decide:
✅ Use a User Story if:
You need to describe what the user wants to achieve.
Agile workflows are being followed.
You want lightweight documentation that encourages collaboration.
✅ Use a Use Case if:
You need to outline step-by-step system behavior.
The workflow has multiple alternate flows or error handling.
Developers and QA need a structured flow of interactions.
✅ Use a Requirement if:
You need detailed system specifications (both functional & non-functional).
The project requires technical documentation or regulatory compliance.
Precise performance expectations and constraints must be defined.
🔥 Pro Tip: Use all three together for a complete picture! A user story captures intent, a use case maps out interactions, and requirements ensure precise implementation. 🚀
5️⃣ Real-World Example: How They Work Together
Let’s say we’re building a password reset feature:
🔹 User Story: "As a customer, I want to reset my password, so that I can access my account if I forget my credentials."
🔹 Use Case: Detailed step-by-step flow of how the customer resets their password, including error handling.
🔹 Requirement: "The system must send the reset email within 60 seconds of the request."
Each one plays a different but complementary role. Together, they ensure everyone — from stakeholders to developers — is aligned.
5️⃣ Real-World Example: How They Work Together
Let’s say we’re building a password reset feature:
🔹 User Story: "As a customer, I want to reset my password, so that I can access my account if I forget my credentials."
🔹 Use Case: Detailed step-by-step flow of how the customer resets their password, including error handling.
🔹 Requirement: "The system must send the reset email within 60 seconds of the request."
Each one plays a different but complementary role. Together, they ensure everyone — from stakeholders to developers — is aligned.
What’s the biggest misunderstanding you’ve seen between user stories, use cases, and requirements in your projects?
Drop your experiences below! 🚀
🔮 Key Takeaways:
User stories, use cases, and requirements each serve a distinct but complementary role in business analysis. User stories focus on what the user wants, use cases map out how the system responds, and requirements define what must be built. Mastering these concepts ensures smoother communication, better stakeholder alignment, and more successful project outcomes. Understanding when and how to use each approach is what sets apart a great BA from an average one.
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Related to this topic, I really like the book "User story mapping" by Jeff Patton. Really helped me understand how to approach these things starting from a very high level all the way down to details. I strongly recommend it if you don't know it already!