Dow 30 or Dow Jones Industrial Average (DJIA) is the best known U.S. index of stocks. The DJIA is an indicator showing how stocks of the largest US companies are performing, thus describing the overall condition of the stock market. The index is calculated as a weighted average of 30 actively traded blue-chip stocks of the New York Stock Exchange.
Additional meaning of Dow 30:
The Dow was started by Charles Dow in 1896. At that time it included 11 stocks. The stocks are chosen by the editors of the Wall Street Journal published by Dow Jones & Company.