Code Injection is a type of security vulnerability that allows an attacker to introduce malicious code into a program or application. This can happen when user input is not properly validated or sanitized, enabling the attacker to manipulate the system's behavior. Common targets include web applications, where injected code can execute commands or access sensitive data. There are various forms of code injection, including SQL Injection, Cross-Site Scripting (XSS), and Command Injection. Each type exploits different weaknesses in software, but they all share the goal of executing unauthorized commands. Preventing code injection requires careful coding practices and regular security testing.