Selenium WebDriver primarily supports:
1. Functional Testing Verifies that web application features work as expected — form submissions, button clicks, navigation.
2. Regression Testing Ensures new code changes do not break existing functionality. This is Selenium''s most common use case.
3. Cross-Browser Testing Validates the application works consistently across Chrome, Firefox, Safari, Edge.
4. Smoke Testing Basic sanity checks on critical features after each build.
5. Acceptance Testing Used with Cucumber/BDD frameworks to validate user stories against acceptance criteria.
Note: Selenium does NOT support performance/load testing (use JMeter), API testing (use Rest Assured), or mobile native apps (use Appium).