What are the different levels of Software Testing?

The different levels of software testing are:

1. Unit Testing: This level involves testing individual components or units of the software to ensure that they function correctly in isolation.

2. Integration Testing: This level involves testing the interaction between different components or units of the software to ensure that they work together as expected.

3. System Testing: This level involves testing the entire system as a whole to ensure that it meets the specified requirements and functions correctly in different scenarios.

4. Acceptance Testing: This level involves testing the software from the end user's perspective to ensure that it meets their expectations and requirements.

5. Regression Testing: This level involves retesting the software after modifications or enhancements to ensure that the existing functionalities have not been affected.

6. Performance Testing: This level involves testing the software's performance and scalability under different load conditions to ensure that it can handle the expected user load.

7. Security Testing: This level involves testing the software's security features and vulnerabilities to ensure that it is protected against potential threats and attacks.

8. Usability Testing: This level involves testing the software's user interface and overall user experience to ensure that it is intuitive, easy to use, and meets the needs of the end users.

9. Compatibility Testing: This level involves testing the software's compatibility with different hardware, operating systems, browsers, and other software to ensure that it can function correctly in various environments.

10. Localization Testing: This level involves testing the software's adaptability to different languages, cultures, and regions to ensure that it can be used by users worldwide.

These levels of testing are typically performed in a sequential manner, starting from unit testing and progressing towards acceptance testing, but they can also overlap or be performed in parallel depending on the project requirements and constraints.