Debt financing is when companies borrow external money to fund projects, or in the case with startups, to kick start operations.
From the lender’s side, interest rate is the percentage compensation received from offering a loan service. From the borrower’s side, interest rate is the percentage cost paid to acquire a loan service.
Trade goes way back, even before the discovery of fiat money people used to exchange goods for goods, a form of trade famously known as barter trade, this was for a long time a means that seemed to work for the better part of the whole community.