Definition of 'Dow 30'
Commonly referred to as just the "Dow," the Dow 30 was created by Wall Street Journal editor Charles Dow and got its name from Dow and his business partner Edward Jones. The index was developed as a simple means of tracking U.S. market performance in an age when information flow was often limited.
Also known as the "Dow Jones Industrial Average".
Investopedia explains 'Dow 30'
A spin-off of the Dow Jones Transportation Average, consisting primarily of railroad issues in the early years, the Dow expanded to 30 stocks in 1928, where it remains today. The composition of the index changes regularly, as stocks and the industries it represents fall in and out of favor.