Fault Injection is a testing technique used in software and systems engineering to identify vulnerabilities and ensure reliability. It involves deliberately introducing errors or faults into a system to observe how it responds. This helps developers understand potential weaknesses and improve the system's resilience against unexpected issues. By simulating various failure scenarios, Fault Injection allows teams to evaluate the effectiveness of their error handling and recovery processes. This proactive approach can lead to more robust applications, as it encourages the identification and resolution of problems before they occur in real-world situations.