Regression testing plays a crucial role in GUI development by:

1. Ensuring changes don't break existing functionality.

2. Verifying bug fixes didn't introduce new issues.

3. Detecting unintended side effects of code changes.

4. Validating functionality after updates or modifications.

5. Ensuring consistency across different versions.

6. Identifying issues that may have been missed during initial testing.

7. Providing confidence in the stability and reliability of the GUI.

8. Reducing the risk of releasing flawed or broken software.

9. Saving time and resources by catching issues early.

10. Supporting continuous integration and delivery.

Regression testing for GUI development involves re-running functional and non-functional tests to ensure the application still works as expected after changes. This includes:

- Re-testing previously working functionality

- Verifying bug fixes

- Testing new features

- Checking for compatibility issues

- Validating performance and security

By incorporating regression testing into the GUI development cycle, you can ensure that changes and updates don't compromise the application's quality and user experience.