Cross-site scripting (XSS) is a prevalent web security issue that can manifest in three types based on vulnerability impact: persistent, reflected, and self-XSS. Persistent XSS is the most severe, where attackers inject malicious scripts that permanently reside on a site, affecting all users who access the compromised page, as exemplified by the Samy worm on MySpace. Reflected XSS involves attackers crafting links that execute scripts from a website, often used for phishing by mimicking login pages to steal credentials. Self-XSS requires user interaction, where attackers trick users into executing scripts themselves by clicking deceptive links. While some popular browsers offer built-in protection against reflected and self-XSS, others rely on plugins such as NoScript to mitigate these vulnerabilities.