As per Wiki-
"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. It is the equivalent of a physical point of sale terminal located in most retail outlets."
As per me - "Give me the money" :-)
Every websites & mobile apps who want to integrate with payments gateways to accept payments online - always are in search for good recommendations to choose. It's a little bewildering initially but there are enough materials online. I have tried to bookmark some of the good materials which have been useful.
Below are the useful links.
Our takeway from reading these articles - Have atleast 2 payment gateways ready if your transaction volume has increased. Hmm.. wise words.