Application Security Testing (AST) is a critical practice in the software development lifecycle, aimed at identifying and addressing vulnerabilities to enhance an application's security. Integral to DevSecOps, AST involves using various security scanners such as Static Application Security Testing (SAST), Software Composition Analysis (SCA), and Dynamic Application Security Testing (DAST) to detect vulnerabilities early in the process. SAST analyzes source code, SCA evaluates open source software for security and compliance, and DAST assesses running applications for runtime vulnerabilities. Additionally, Interactive Application Security Testing (IAST) and container scanning tools are employed to test application behavior and containerized environments, respectively. The shift-left approach, which emphasizes early testing in the development cycle, along with automation and clear communication of vulnerability information, are best practices to minimize disruption and expedite remediation. Harness Security Testing Orchestration (STO) enhances this process by integrating with CI/CD pipelines to facilitate rapid and effective vulnerability management through prioritization and AI-driven solutions.