What is software testing?
Software testing investigates whether a system behaves as expected and where it fails.
How it works and where it is used
Unit, integration, end-to-end and exploratory tests answer different questions. Test data, boundary cases and failure scenarios should reflect reality. A green suite does not prove untested behavior is correct. A useful test explains why its expected outcome matters.
Limits, safety and selection criteria
Prioritize user impact, security and change risk rather than only line coverage. Flaky tests erode trust. Tests need maintenance as requirements, external services and time-dependent behavior change. Testing a registration form only with valid data misses empty fields, long text, concurrent signups, network loss and accessible error messages. Risk determines what to automate and what to explore manually. Production monitoring can reveal gaps that tests missed, feeding new regression cases. Using real personal data in test fixtures creates privacy risks. When a defect appears, record steps and expected versus actual behavior so the team can reproduce it. Good testing improves learning about the product, not just the number of green checks.