Content Security Policy

Content Security Policy (CSP) is a web security standard that helps prevent cross-site scripting (XSS), clickjacking, and other code injection attacks by allowing website administrators to specify which sources of content are trusted and allowed to execute. It works by defining a set of directives in HTTP headers or meta tags that restrict where resources like scripts, styles, and images can be loaded from. This reduces the risk of malicious content being injected and executed in a user's browser.

Also known as: CSP, Content-Security-Policy, Content Security, Web Security Policy, Security Headers

Why learn Content Security Policy?

Developers should learn and implement CSP when building web applications that handle sensitive user data or require high security, such as banking sites, e-commerce platforms, or any service vulnerable to XSS attacks. It is particularly useful in modern web development to mitigate client-side security threats and comply with security best practices, as it provides an additional layer of defense beyond input validation and sanitization.

Learning Resources

• docs: MDN Web Docs: Content Security Policy
• tutorial: Google Web Fundamentals: Content Security Policy
• docs: OWASP Cheat Sheet: Content Security Policy
• tool: CSP Evaluator by Google
• video: YouTube: Introduction to Content Security Policy