The most common bank of all is the commercial bank, which may be a national bank, a state bank, or a private bank. It gets its name from the fact that it confines its business largely to business men, receiving their deposits and cashing their checks as they come in. Commercial bank loans are almost invariably for short periods of time, usually thirty, sixty, or ninety days. Hence its funds are liquid. Contrary to the generally accepted notion among some classes of people, a commercial bank is anxious for its customers to borrow its funds for carrying on their business. Its profits depend almost entirely on its volume of loans, and its prosperity is intimately bound up with the prosperity of its customers. For these reasons the typical American banker encourages legitimate business expansion, and treats his borrowers with the greatest liberality consistent with safety. He is in fact more of a public official than most people think, for his business must be conducted with due regard for the well-being of society as well as for private gain.