PayPal Payment (REST API) (Current)Payee (Merchant) SitePayee (Merchant) SitePayer (Shopper) BrowserPayer (Shopper) BrowserPayer (Shopper) PSP (PayPal)Payer (Shopper) PSP (PayPal)MPSPMPSPHTTPS1Present Checkout Page with Pay Button2Select PayPal Payment Method3Payment Page Request4Create Payment5HTTP RedirectHTTP Direct now send the shopper to the PayPal site6Payment Initiation7Authentication Page8AuthenticateTypically a username & password9Payment Pageopt10Instrument ChoicePayer can change from default payment instrument11Approval12Payment Approval13Payment Response Redirect14Payment Response15Execute Payment16Result Pageasynchronous notification17Payment Notification (email)opt18Payment Notification (email)