A: Medical billing and coding is the process of assigning codes to medical procedures and diagnoses, and submitting claims to insurance companies or other payers for reimbursement. These codes, known as International Classification of Diseases (ICD) codes and Current Procedural Terminology (CPT) codes, are used to accurately describe the medical services provided to patients and to standardize the billing process. Medical billing and coding professionals are responsible for preparing and submitting claims, and for following up on unpaid or denied claims.