A medical billing company in the USA is an organization that manages the healthcare revenue cycle for clinics, hospitals, and private practices by handling patient billing, insurance claims, and payment processing. These companies work as an extension of healthcare providers, ensuring that medical services are coded accurately, claims are submitted to insurance companies on time, and denied claims are followed up to secure proper reimbursement. They also assist with patient eligibility verification, payment posting, compliance with healthcare regulations, and maintaining HIPAA privacy standards.