Cross-Site Scripting
Cross-Site Scripting (XSS) is a web security vulnerability that allows attackers to inject malicious client-side scripts into web pages viewed by other users. It occurs when a web application includes untrusted data in its output without proper validation or escaping, enabling the execution of scripts in the victim's browser. This can lead to data theft, session hijacking, defacement, or malware distribution.
Developers should learn about XSS to build secure web applications and protect against common attacks that exploit user input. It's crucial for roles involving front-end development, full-stack engineering, or security, especially when handling user-generated content like comments, forms, or URLs. Understanding XSS helps implement defenses such as input validation, output encoding, and Content Security Policy (CSP).