Paypal is probably the most popluar payment method on the internet. Large amount of our payments are processed by Paypal. The principle of paypal is to work as a payment gateway between the customer and the company. It means that you are able to transfer funds from your personal bank account or credit/debitcard to the Paypal service and use these funds in future payments. Payments made via Paypal are automatically verified in seconds, so there's practically no delay after payment before the product is delivered to you.
Basically after registering to the Paypal service, it is easy to pay for a product with your Paypal account and there's no more hassle with credit/debitcard numbers for example.