What are the three types of credit?

I know there is Revolving Credit, Installment Credit, but what is the third type of credit?

The third is open credit where the balance has to be paid within a fixed period of time, often 30 days. It is most often used in business.

Some suppliers offer "terms" to insure the bills are paid on time. For an example, they might add 5 percent to the price of all of their products and offer 5% off if paid within 30 days, 2% in 60 days and net 61.