Loans are typically structured agreements with pre-defined time horizons, premiums, and payback schedules. A loan is a scenario in which one party lends another party some arbitrary asset with the expectations of full repayment plus a premium for the service.
Arnold needed $300 to pay for his birthday party. He could not ask his job for payment advance so he decided to ask his friend, Brian, for a loan. Brian said he could only loan him the money if Arnold agreed to pay him back $312 by next month. Arnold Agreed had an amazing birthday party and paid back Brian $312 the very next day! Brian said from here on in if Arnold needs a loan he will give it to him.