In the United States, the federal funds rate is the interest rate at which depository institutions (banks and credit unions) lend reserve balances to other depository institutions overnight, on an uncollateralized basis. Wikipedia
This rate is determined by the Federal Reserve. It is manipulated to stimulate the economy during periods of recession. It is lowered to stimulate the economy. As you can see from the chart below, the funds rate has never been near zero for this many years. What are the consequences of this rate? The bubble that was created will burst. This time the bubble includes student debt, auto loans, business debt, government debt, mortgage debt, and credit cards. This bursting will happen within the near future. Take cover!