A payment gateway is an e-commerce application service provider service that authorizes credit card payments for e-businesses, online retailers, bricks and clicks, or traditional brick and mortar.
A payment gateway facilitates the transfer of information between a payment portal (such as a website, mobile phone or interactive voice response service) and the Front End Processor or acquiring bank.
Also it will create Payment Gateway Account entry. Payment Gateway Account is configuration hub from this you can set account head from existing COA, default Payment Request email body template.