Paypal Standard is a feature of Paypal Payments and is integrated by default in Magento.

Paypal allows to capture the amount of the order. The Seller can use a registered and approved Paypal email for a business account. He can enter this email in the configurations of Paypal and enable Paypal Standard to capture the orders amount from buyers. Once buyer selects the products to purchase and places order from the checkout, he is redirected to Paypal page where he can pay using his account credentials or by using his credit card details. Once paid, he is redirected back to the success page of the site.
This tag denotes all the issues related to the Paypal's Standard checkout feature.