The concept of lending and borrowing is as old as time itself. Regarding finances, while some individuals have more than enough for themselves, others barely have enough to get by. As long as there is this imbalance in finance distribution, there will always be a need to borrow and a desire to lend.
Lending involves giving out a resource on credit with the condition of it being returned upon an agreed period of time. In this case, such resources would be money or any financial asset.
The lender could be an individual, a financial institution, a firm or even a country. Whichever the case may be, the lender, oftentimes, needs a sort of assurance that their resources would be returned to them upon the agreed time.