VISA is considered the world’s largest card payment service provider. It is so big that it controls about 70% of the global market. (Surprisingly, the rest of the market belongs to Chinese UnionPay, not MasterCard.)
Visa is used worldwide for 100 trillion transactions each year which is worth 7 trillion dollars in value. Contrary to popular belief, VISA is not a “bank”. It cannot see your credit score or check your bank account.