Have you had experience writing Use Cases and User Stories?

Yes, I have experience in writing Use Cases and User Stories. A Use Case describes the interaction of a user with the system to achieve a specific goal, including main and alternative scenarios. A User Story is a brief description of a feature from the user's perspective, usually in the format: "As a [role], I want [feature], so that [goal]."

For example, a User Story for an online store:

As a shopper, I want to add an item to the cart so that I can place an order later.

A Use Case for the same story might include steps:

1. The user selects a product.
2. Clicks the "Add to cart" button.
3. The system updates the cart contents.
4. The user sees a confirmation of addition.

This approach helps clearly define requirements and usage scenarios of the system.