Diagnostic error refers to mistakes or failures in the process of diagnosing a patient's condition or illness. This can occur at any point in the diagnostic process, such as obtaining a medical history, conducting physical exams, ordering tests, interpreting test results, or formulating a final diagnosis. Diagnostic errors can have serious consequences for patients, including delayed or incorrect treatment, unnecessary tests or procedures, and even death. Research in this area aims to understand the factors contributing to diagnostic errors, develop strategies to prevent them, and improve the accuracy and efficiency of diagnostic practices in healthcare.