The world of money fits into four broad categories or transactions:
Business to business payments: a 20T dollar global industry where businesses conduct commerce between them to pay for material used in producing goods or services that are then sold to retailers.
Consumer to business payments: a 20T dollar industry where consumers buy goods and services from businesses around the world.
Business to consumer payments: a trillion dollar industry where businesses disperse payments for sales commissions, rebates, refunds, payroll, pension payments etc..
Consumer to consumer payments: a trillions dollar industry where consumers send money to each other for support purposes, to help pay for schools, emergencies, gifts, etc..
The world of money is conducted on very complex payment systems that vary from country to country. There are over 10 types of payments: cards, bank push payments (real time and delayed), cash, prepaid, post paid, wallets, vouchers, gift cards, etc.. In addition, every country has it set of payment types and local brands. If you are a business conducting global commerce, understanding the nuances, the types of payments available in each country and what is doable is a major task. There are over 200 payment brands around the world (e.g. Visa, MasterCard, Amex, PayPal, IDEAL, BPAY, AliPay, and the list goes on and on) and they all have their set of issues not only with the payment processing, but with the exceptions, refunds, and the management of the lifecycle of these payments