What is the difference between a user story and a use case?

User story and use case are two different ways of describing system requirements, but with different levels of detail and purpose.

User story is a short, simple description of functionality from the user's perspective, usually in the format: "As a [user type], I want [goal], so that [benefit]." User story focuses on user needs and the value they receive. It is a lightweight tool often used in Agile for planning and prioritization.

Use case is a more formal and detailed description of the interaction between the user (actor) and the system to achieve a specific goal. A use case includes scenarios, steps, alternative paths, and exceptions. It helps understand the system's logic and serves as a basis for design and testing.

Example of a user story:

As a registered user, I want to reset my password so that I can access my account if I forget my password.

Example of a use case (brief):

• Actor: Registered user
• Goal: Reset password
• Main scenario:
  1. The user clicks "Forgot password".
  2. The system requests email.
  3. The user enters email.
  4. The system sends an email with a link to reset the password.
  5. The user clicks the link and enters a new password.
  6. The system confirms the password change.

Thus, a user story is a brief description of a need, and a use case is a detailed description of the interaction.