Selenium is a popular open-source framework primarily used for automating web browser interactions. It is commonly used for testing web applications, especially in the context of functional and regression testing. With Selenium, you can automate the testing of various aspects of web applications, including:

1. User Interface Testing: Selenium allows you to simulate user interactions with a web application by programmatically clicking buttons, filling out forms, selecting dropdown options, and verifying the resulting page elements.
2. Functional Testing: You can use Selenium to verify that the various functionalities of your web application are working as expected. This involves automating scenarios like logging in, adding items to a shopping cart, or submitting forms.
3. Regression Testing: Selenium can be employed to automate the process of testing whether recent changes to the codebase have introduced any new bugs or issues, ensuring that previously working features remain functional.
4. Browser Compatibility Testing: By running Selenium tests across different web browsers and browser versions, you can identify and address compatibility issues specific to certain browsers.
5. Performance Testing: While not the primary focus, Selenium can be used to simulate multiple user interactions and help evaluate the performance of a web application under different loads.
6. Data-Driven Testing: Selenium can be integrated with test data sources to run tests with various input values, making it useful for data-driven testing scenarios.
7. Integration Testing: You can integrate Selenium tests with other testing tools or frameworks to create more comprehensive integration tests that cover interactions between different components of your application.
8. Continuous Integration (CI) and Continuous Deployment (CD): Selenium tests can be incorporated into your CI/CD pipeline to ensure that new code changes do not introduce regressions and that your application maintains a high level of quality throughout its development lifecycle.

Selenium supports multiple programming languages, such as Java, Python, C#, and more, making it versatile and widely used in various development environments.

In summary, Selenium is a powerful tool for automating browser interactions, making it an excellent choice for testing web applications across different scenarios and requirements.