Hex encoding (also known as hexadecimal encoding) involves converting binary data into hexadecimal representation. In the context described, when a user submits a request with potentially malicious input (such as a single quote and other characters in an attempt to perform SQL injection), the encoding technique converts this input into a string of hexadecimal digits (ranging from 0 to 9 and A to F). This prevents the direct interpretation of the input as SQL commands by the database, thereby mitigating the risk of SQL injection attacks. This method is a form of input sanitization that helps ensure that user input cannot be used to manipulate database queries directly.