The Dow Jones Industrial Average is a stock index of 30 large US companies, weighted by share price rather than company size.
Created in 1896, it is one of the oldest market indexes. Because it is price-weighted, a stock with a high share price moves the Dow more than one with a low price, regardless of company size.
Why it matters to you
It is widely quoted in the news, but the S&P 500 is a broader measure of the market.