A banker or bank is a financial institution that acts as a payment agent for customers, and borrows and lends money. In some countries such as Germany, banks are the primary proprietor of manufacturing corporations while in other countries such as the United States banks are banned from owning non-financial companies. In Japan, banks are usually the nexus of cross share holding entity known as zaibatu.

Banks act as payment agents by conducting checking or present accounts for customers, paying checks drawn by customers on the bank, and collecting checks consign to customers' current accounts. Banks also enable customer payments via other payment methods such as telegraphic assign, EFTPOS, and ATM.

Banks borrow money by uncomplaining funds deposited on current account, accepting term deposits and by issuing debt securities such as banknotes and tie. Banks lend money by making advances to customers on current account, by making installment loans, and by investing in saleable debt securities and other forms of lending.

Banks provide almost all payment services, and a bank account is considered indispensable by most businesses, individuals and leadership. Non-banks that provide payment services such as remittance companies are not normally considered an sufficient substitute for having a bank account.

Banks borrow most funds borrowed from households and non-financial businesses, and lend most funds lent to family and non-financial businesses, but non-bank lenders provide a significant and in many cases adequate substitute for bank loans, and money market support, cash management trusts and other non-bank financial institutions in many cases provide an adequate substitute to banks for lending savings to.