Application security is crucial in software development as it focuses on identifying and mitigating vulnerabilities within applications. This ensures that software is protected against threats such as data breaches and malware attacks. By embedding security practices throughout the development lifecycle, businesses can avoid costly consequences associated with security lapses. Implementing strategies like code reviews, penetration testing, and secure coding standards enhances the overall integrity of applications. Ultimately, effective application security fosters user trust and protects sensitive data from unauthorized access.