Maximillian Schwanekamp wrote: As web developers I don't think it's for us to explain > the inner workings of payment processing, though for general audience it > might be good to have links to more technical info. This is a general statement....:) If, as a web developer, you are not in tune with what your client does to make money, to hire a web developer, your career will not be long or profitable. This includes but not limited to how the client makes money from supplier to customer including all of those little details such as offline marketing, physical plant, computer literacy, types of payments, warrantees, return policies, service after the sale, business group, memberships, community involvement, charities, work environment, employee satifaction, benefits, bookeeping, payment scheduling, credit worthiness, and so on. Too many folks get into pixel mechanics and think that pretty pictures in the browser does the job. Most of these folks pursue other careers quickly. In building websites for business, you are in business, with a lot of the same challanges that your clients have. Without understanding your client's business, you cannot effectively do your job, which is to put pretty pictures in the browser to make money for the client. That you get paid is gravy.