Web applications represent numerous sensitive business processes within companies - whether with customers, employees, partners, or suppliers. Therefore, web applications pose a security risk for businesses, and their protection is of paramount importance. In this book, the author highlights the key aspects of web application security, drawing on his extensive experience as an IT security consultant for web applications and development processes. The volume provides not only a general overview of the topic of web application security but also detailed and practical presentations on important individual issues: What are the most common vulnerabilities, and what measures can be taken to effectively secure web applications against attacks? A dedicated chapter addresses the methods used to ensure the security of applications during the development process.