What is Bank and how it works ?

That bank can then lend out €81 of that €90 deposit, and that €81 goes into the economy to purchase goods or services and ultimately is deposited into another bank that proceeds to lend out a percentage of it.

In this way, illustrated below, money grows and flows throughout the community in a much greater amount than physically exists. That initial €100 deposit makes a much larger ripple in the economy than you may realise!