What is manual testing vs automated testing?

Manual testing is performed by human testers who execute test cases without automation tools — exploring the application, simulating user behavior, and reporting defects. Advantages: (1) Human judgment — can detect UI/UX issues, inconsistencies that automated tests miss. (2) No setup investment. (3) Better for exploratory testing and usability. (4) Good for one-time tests. Disadvantages: slow, expensive at scale, error-prone (humans miss things), not repeatable exactly. Automated testing uses code/tools to execute tests. Advantages: speed (run 1000 tests in minutes), repeatability, 24/7 execution in CI, catches regressions instantly. Disadvantages: upfront investment in writing tests, maintenance burden, can't easily test subjective qualities. Best practice: automate what's valuable and stable; use manual testing for exploration, new features, accessibility, and human judgment scenarios. The goal is not to eliminate manual testing but to make automated testing handle the regression burden, freeing humans for high-value exploration.