A QA Tester ensures software quality through systematic testing to identify bugs and ensure functionality meets specifications. Key responsibilities include designing test plans, executing tests, and documenting results. Skills in attention to detail, problem-solving, and knowledge of testing tools are essential. Typically working in agile teams, QA Testers collaborate closely with developers and product managers. Career progression may lead to roles like QA Lead or Test Manager, enhancing growth opportunities in software development or quality assurance leadership.