A bank is a financial intermediary that accepts deposits and channels those deposits into lending activities, either directly or through capital markets. A bank connects customers with capital deficits to customers with capital surpluses.

Banking is generally a highly regulated industry, and government restrictions on financial activities by banks have varied over time and location. The current set of global bank capital standards are called Basel II. In some countries such as Germany, banks have historically owned major stakes in industrial corporations while in other countries such as the United States banks are prohibited from owning non-financial companies. In Japan, banks are usually the nexus of a cross-share holding entity known as the keiretsu. In Iceland banks had very light regulation prior to 2008 collapse.