Application security testing is the process of finding vulnerabilities in applications after release through methods like fuzzing, bytecode manipulation, and regression testing. Application security software helps prevent threats by scanning applications with static analysis or penetration testing. Application security testing is important to reduce security risks and vulnerabilities, which helps reduce attacks. It involves phases like understanding threats, discovering vulnerable points, and fixing flaws. Types of security testing include static, dynamic, penetration, interactive, and mobile application testing as well as software composition analysis. Dynamic application security testing examines the application frontend through simulated attacks to identify vulnerabilities from outside the application.