Pay Methods are payment methods that belong to a client, like credit cards or bank accounts. They can apply to orders and invoices.
Payment gateways allow you to accept payments of many types in WHMCS. You can use one of WHMCS's many supported gateway modules or create your own.
WHMCS includes several supported payment gateway modules for accepting payments through PayPal®, including the new PayPal Payments gateway.
Disputes, including chargebacks, inquiries, or retrievals, occur when a client contests charges that you collected from their card issuer.
Tokenization stores sensitive payment details remotely using a payment gateway processor. WHMCS supports many tokenized payment gateways.
If a module for your payment gateway doesn't exist yet, you can develop your own custom payment gateway modules using the examples here.
Troubleshoot and resolve Chrome™ browsers crashing when your customer makes a payment using 2Checkout.