The core concepts every QA engineer is expected to know — explained properly, from the ground up. This playlist covers testing principles, test levels and types, black-box and white-box techniques, test design methods like equivalence partitioning and boundary value analysis, defect life cycles, and the terminology that comes up in every QA conversation and interview. Start here if you're new to testing, or brushing up before an interview. 🔗 Full written guides, glossary and cheat sheets: qa.codes