A chief loan is the simplest form of debt. It consists of an acknowledging to lend a principal sum for a fixed period of time, to be repaid by a certain date. In financial loans interest, calculated as a percentage of the principal sum per annum, will also have to be paid by that date.
As noted above, debt is abnormally denominated in a particular monetary currency, and so changes in the valuation of that currency can change the effective capacity of the debt. This can happen due Credit Card Debt to inflation or deflation, so it can happen even though the borrower and the lender are using the same currency. Thus it is important to agree on standards of deferred outlay in advance, so that a degree of fluctuation will also be agreed as acceptable. It is for instance colloquial to agree to "US dollar denominated" debt.