A bank is a financial institution that serves as a financial intermediary. The term "bank" may refer to one of several related types of entities:

A central bank circulates money on behalf of a government and acts as its monetary authority by implementing monetary policy, which regulates the money supply.
A commercial bank accepts deposits and pools those funds to provide credit, either directly by lending, or indirectly by investing through the capital markets. Within the global financial markets, these institutions connect market participants with capital deficits (borrowers) to market participants with capital surpluses (investors and lenders) by transferring funds from those parties who have surplus funds to invest (financial assets) to those parties who borrow funds to invest in real assets.
A savings bank (known as a "building society" in the United Kingdom) is similar to a savings and loan association (S&L). They can either be stockholder owned or mutually owned, in which ...more

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B=Borrowing
A=Accepting
N=Negotiating
K=Keeping