The FOMC cited concerns over global economic conditions as the primary reason for not raising rates.
The FOMC doesn’t directly affect all interest rates in the American economy. Instead, “the Fed” sets the overnight rate which banks use to charge interest for loans between them.
Indirectly, the overnight rate affects credit cards, car loans and ultimately home loans as banks offset their borrowing costs by passing the increase on to their customers.
Had the Fed increased rates, consumers would likely have seen credit card minimum payments increase and future home/car buyers might have to provide a larger down payment or buy less car or house.
Market reaction as of 2pm eastern was a slight reversal from a 48 point gain in the Dow industrials to a 41 point loss.