PayPal Express Checkout allows merchants to offer a streamlined checkout process that keeps buyers on their site. It allows merchants to create recurring payment profiles during checkout. When a profile is created, PayPal will automatically queue payments based on the billing details. Merchants can then use the Recurring Payments API to get details, change statuses, update profiles, and bill outstanding amounts of recurring profiles. The typical Express Checkout flow involves setting up the transaction with PayPal, redirecting the buyer to PayPal to select payment, and then creating any recurring profiles on the backend.