HTML Encoding

HTML encoding is a security technique that converts potentially dangerous characters in user input into their corresponding HTML entities, preventing them from being interpreted as HTML or JavaScript code by web browsers. It is primarily used to defend against cross-site scripting (XSS) attacks by ensuring that data displayed on web pages is treated as plain text rather than executable code. This process involves replacing characters like <, >, &, and " with safe equivalents such as &lt;, &gt;, &amp;, and &quot;.

Also known as: HTML escaping, HTML entity encoding, XSS prevention encoding, HTML sanitization, Character encoding for HTML

Why learn HTML Encoding?

Developers should use HTML encoding whenever displaying untrusted user input on web pages to prevent XSS attacks, which can steal sensitive data or hijack user sessions. It is essential in web applications that handle form submissions, comments, or dynamic content from external sources, such as social media feeds or APIs. Proper encoding ensures data integrity and user safety by neutralizing malicious scripts before they reach the browser.

Learning Resources

• docs: OWASP XSS Prevention Cheat Sheet
• docs: MDN Web Docs: HTML Entity
• tutorial: FreeCodeCamp: Prevent XSS Attacks with HTML Encoding
• course: Pluralsight: Web Security Fundamentals