By transforming clinical data into standardised codes for recording, invoicing, research, and policymaking, medical coding plays a critical role in the healthcare industry. ICD for illnesses, CPT for procedures, and HCPCS for extra services and supplies are important systems. Their evolution, uses, and significance in clinical practice, reimbursement, and public health are examined in this review. It also draws attention to issues like version changes, coding mistakes, and the requirement for qualified personnel. Adoption of ICD-11, automation powered by AI, and data analytics are examples of emerging trends that seek to improve global standardisation and guarantee precision, effectiveness, and uniformity in the provision of healthcare.