The Bottom Line
For most merchants, customers pay via an online shopping cart and checkout system. You can build your own shopping cart as part of your e-commerce website, contract with a third-party to provide shopping cart services, or use the PayPal Shopping Cart included free with PayPal's Website Payments Standard. When you use the PayPal Shopping Cart, you can specify taxes and shipping fees, customize the payment pages your customers see, and configure how you deal with transactions in foreign currencies.
If you offer subscriptions or other services that require recurring payments, PayPal lets you add a Subscription button to your site, along with corresponding information on the recurring payments. And if your business is one where the customer is billed for goods or services, you can use PayPal's Online Invoicing to email invoices to your customers; customers can pay the invoice by clicking the PayPal payment button included within it.