Dow Jones

Turn on the news on any given day, and you're likely to hear about the Dow Jones industrial average. It is the most frequently checked, and cited, proxy of U.S. economic health. But a lot of people — maybe most — don't even know what it is. It's just the stock prices of 30 big companies, summed up and roughly averaged. That's it.

And what does the daily movement of this number have to do with the lives of most Americans? Not much.