Credit card chargebacks occur when a customer disputes a transaction and requests reimbursement from their credit card issuer. Merchants can receive chargeback fees of $20-100 per dispute. To prevent chargebacks, merchants should obtain proper customer verification, comply with PCI security standards, verify customer identities, reject expired or unsigned cards, and educate employees on card handling procedures. Understanding potential reasons for chargebacks like fraudulent use, unauthorized transactions, or undelivered goods allows merchants to dispute charges and potentially avoid fees.