INVEST is an acronym that stands for Independent, Negotiable, Valuable, Estimable, Small, and Testable. It is a set of criteria used to evaluate the quality of user stories and ensure that they are well-formed and effective.

Here's a breakdown of what each of the INVEST criteria means in relation to user stories: 

1. Independent: User stories should be independent of one another, meaning they should not depend on other stories. Each story should be able to stand on its own and be completed in isolation.

2. Negotiable: User stories should be flexible and open to negotiation. They should not be so rigid that they cannot be changed or refined as needed.

3. Valuable: User stories should provide value to the user or customer. They should address a real need or problem and provide a benefit when implemented. 

4. Estimable: User stories should be able to be estimated in terms of the effort required to implement them. This helps the team plan and prioritize their work effectively.

5. Small: User stories should be small enough to be completed in a single sprint or iteration. They should not be so large that they cannot be completed within a reasonable timeframe.

6. Testable: User stories should be testable, meaning that there should be a clear definition of what constitutes success for the story. The team should be able to define acceptance criteria that can be used to verify that the story has been completed successfully. 

By ensuring that your user stories meet these INVEST criteria, you can help to ensure that they are well-formed and effective in driving the development of your product or system. To know more about the Business Analyst program, please click here.