Diagnostic systems are tools or methods used to identify and analyze problems or conditions in various fields, such as medicine, engineering, and information technology. In healthcare, for example, these systems help doctors determine the cause of a patient's symptoms through tests and evaluations, leading to accurate diagnoses and effective treatments. In engineering, diagnostic systems monitor machinery and equipment to detect faults or inefficiencies. By analyzing data from sensors and performance metrics, these systems can predict failures and suggest maintenance, ultimately improving reliability and reducing downtime. Examples include automated diagnostic tools and predictive maintenance software.