This text is a tutorial on how to improve the security of an Express.js application by using the helmet module. The author starts with setting up a new project and installing the necessary modules, including Express and helmet. They then configure the helmet middleware to add several security headers to the responses, including X-Powered-By, which is removed, as well as X-DNS-Prefetch-Control, X-Frame-Options, Strict-Transport-Security, X-Download-Options, X-Content-Type-Options, and X-XSS-Protection. The author explains what each of these headers does and how they can help protect against common web vulnerabilities such as cross-site scripting (XSS) attacks. They also discuss the use of Content Security Policy (CSP), which allows developers to specify a set of rules that define which sources are allowed to load resources on their page, helping to prevent XSS attacks. The author provides examples and explanations for how to configure these headers in Express.js applications, as well as links to additional resources for learning more about web security best practices.