Medical billing refers to the process of submitting and following up on claims with health insurance companies in order to receive payment for services rendered by a medical provider. This involves compiling all relevant information about a patient's visit, including diagnosis codes, procedure codes, and any applicable charges or fees, and then submitting this data to the insurer for review and potential reimbursement. Medical billers may also work with patients to help them understand their coverage and out-of-pocket costs, as well as assist in appealing denied claims. Overall, medical billing is a crucial aspect of ensuring that healthcare providers are able to continue offering care while maintaining financial stability.