Dow Jones Industrial Average

Dow Jones* often refers to the Dow Jones Industrial Average, which was one of the first stock indices and is one of the most commonly referred to barometers of equity performance in the United States. The Dow Jones Industrial Average, not to be confused with the Dow Jones Transportation index (which was the first index), is often called, "the Dow" or "DJIA," and consists of thirty stocks which traditionally were industrial-based. But in recent years as the US economy has become more consumer-oriented, the index has seen a change in composition that no longer has much to do with direct industrial investment.

Dow Jones has the longest history.  It includes mainly business in heavy industry, and does not include public utilities or transportation related businesses.