Founded by Charles H Dow.
Dow Theory is used to understand demand and supply.
It is to study about demand and supply using the traded price and volume.
Daily line chart to be used, Minimum 2 year period, Bulling or Bearish trend can be determined.
Duration – depends as long as Higher Bottom, Higher Top is not negated – remain bullish. As long as Lower Top, Lower Bottom is not negated remain bearish.