Cross-site Scripting (XSS) is a type of security vulnerability found in some websites and web applications that accept user input. It is when malicious scripts are injected into web pages in the form of browser side script, to be sent to unsuspecting users. It occurs when the web application accepts user input without validating or encoding it. Unfortunately, the end user’s browser will not be able to recognize that the script has been tampered with and will assume that it has come from a trusted source.