Express Checkout is a Name-Value Pair or Simple Object Access Protocol (NVP/SOAP) integration method to receive payment to your business PayPal account.

Integrating Express Checkout will allow your customers to complete transactions in a few steps. Their shipping and billing information is stored securely at PayPal. They don't have to re-enter it on your site. When this integration method is configured with default settings, buyers must have a PayPal account to complete payment. 

PayPal Express Checkout consists of three APIs: 

• SetExpressCheckout indicates to PayPal that you're using this integration method to obtain payment. Your customer is redirected to PayPal to log in, pick a funding source and shipping method. SetExpressCheckout returns a token that you use in the remaining two API calls. 
• GetExpressCheckoutDetails (optional) returns details about the customer who is checking out. This includes shipping address, name, etc. Pass the token PayPal returned on SetExpressCheckout, and PayPal returns the customer's details. 
• DoExpressCheckoutPayment is your request for payment, which you call when the customer has clicked Pay on the final order page. Pass the token and other data, and PayPal returns a Transaction ID along with specific payment details.