Back to School – Questions about the concept of the Bills of Exchange

It is back to school for me this semester, and it is the second week of the school term. I am taking Evidence, Aviation law, Banking Law, and Advanced torts. I find banking law the most confusing of all the subjects. In part, I am not that familiar with the rationale for the different method of business financing, and the legalese used to describe the various parties involved in a transaction can be confusing. There is this concept known as the Bill of Exchange which is purportedly used commonly in international business dealings. I believe that this video on youtube explains the concept well, although I am still a little hazy on the rationale for such a method for business financing. For one, I am not sure what is the advantage of such manner of financing over a simple bank loan. I might be missing something in my understanding of the Bill of Exchange, but my understanding of it is that the seller of goods allows the buyer to pay for the goods at a later date on condition of a promise written in a legal document known as a Bill of Exchange that the seller buyer would pay at a later date. The seller then takes his copy of the Bill of Exchange and trades it in with the bank for money. The bank collects the money from the buyer at a later date. I wonder though why the buyer doesn’t just loan from the bank to buy the goods and pay the bank back at a later date.