Software testing plays a crucial role in software quality management. This paper provides an overview of the basic concepts and principles of software testing, including definitions, principles such as early defect detection, equivalence class division, boundary value testing, and wrong speculation. The classification of software testing is also discussed, covering functional testing, performance testing, safety testing, and compatibility testing. The software testing lifecycle is outlined, including the planning, design, execution, and evaluation stages. Additionally, the paper explores the role of software testing in different phases of the software development process, such as demand, design, encoding, and integration. The specific applications of software testing in quality planning, assessment, and defect management are discussed as well. The future development trends of software testing, including automation, integration with DevOps, and integrity verification, are highlighted. In conclusion, software testing is essential in ensuring software quality, and advancements in automation and integration are expected to shape its future.