Banking & Federal Reserve System

One of the most important ways that the Fed ensures safety and soundness of the banking system is by helping banks respond to all kinds of crises. One way the Fed does this is by making short-term loans to banks through its discount window. This not only helps individual banks and their customers, but also ensures that a shortage of funds at one institution does not disrupt the flow of money and credit in the entire banking system.

Source: https://www.stlouisfed.org/education/in-plain-english-video