What is testing in general?

Testing is the process of verifying software to identify defects and assess compliance with requirements. It helps ensure that the system functions correctly, reliably, and securely.

Main testing tasks:

• Functionality verification — whether the program's behavior matches specifications.
• Error and bug detection.
• Quality and stability assessment.
• Prevention of regressions during changes.

Testing can be manual or automated, include different levels (unit, integration, system) and types (functional, load, security, etc.).

Example: when developing a web application, a tester checks that the submit button actually sends data and displays an error message on incorrect input.