Diagnosis codes are alphanumeric codes used by healthcare providers to identify and classify medical conditions and diseases. These codes are essential for billing, insurance claims, and maintaining patient records. The most commonly used coding systems are the International Classification of Diseases (ICD) codes, which provide a standardized way to document diagnoses across various healthcare settings. These codes help ensure that patients receive appropriate care and that healthcare providers are reimbursed for their services. By using diagnosis codes, medical professionals can track health trends, conduct research, and improve patient outcomes through better data analysis and reporting.