What else is important to know besides the platform and testing device?

Principles and methodologies of software development (Agile, Waterfall). Software development life cycle (SDLC) and testing life cycle (STLC). Task management systems (Jira, Trello). Version control systems (Git, SVN). Databases and SQL. API testing (SOAP, REST). Performance testing tools (JMeter, LoadRunner). Test automation tools (Selenium WebDriver, Cypress, Playwright). Test automation frameworks (TestNG, JUnit, Pytest). CI/CD pipelines and tools (Jenkins, GitLab CI, GitHub Actions). Test design techniques (Boundary Value Analysis, Equivalence Partitioning, Decision Tables). Types of testing (functional, regression, integration, system, acceptance). Defect reporting (bug reports): clear description, reproduction steps, expected and actual results. Communication skills and teamwork. Understanding of the product domain. Software quality metrics. Debugging tools (browser developer console).