What role do financial intermediaries play in the domestic financial system?

I have to separate it into to parts. The financial intermedairies which are banks that borrow their customers money and pay interest on that borrowed money to lend to other customers with the plan of making a return on their investments for them and their customers.

Domestic to me would be the personal home needs such as, a individual (not business) that is looking for a depository institution where he or she can gain interest on the deposited funds or for a bank to finance them so they can purchase a home, car, etc.

I am still researching, but this is what I understand of what I have already researched. Of course I am a student, not an educator, so this is just my opinion.