Definition
Output encoding is the process of transforming data so that it is interpreted as literal data rather than executable code when it is displayed or processed by another system. This technique is crucial for preventing injection attacks where malicious input is disguised as legitimate commands. By escaping or neutralizing characters that have special meaning in a target context, output encoding ensures that user supplied data is treated as harmless text. For instance, when displaying user comments on a web page, output encoding converts characters like '<' and '>' into their HTML entity equivalents, preventing cross site scripting (XSS) attacks. It is important to distinguish output encoding from input validation, which checks data at the point of entry, as output encoding addresses risks at the point of display. This concept is fundamental to web application security and appears on exams like Security+ and CISSP.