What levels of testing are applied when testing this application?

The following levels of testing are usually applied when checking an application:

• Unit Testing — testing individual components or classes for correctness.
• Integration Testing — testing the interaction between modules or services.
• System Testing — testing the entire application as a whole in conditions close to real operation.
• Acceptance Testing — verifying that the application meets the customer's requirements.

Depending on the project, other types may also be used, such as load testing or security testing.