Dow theory is developed by charles h dow. He is 1900s guy. Dow theory helps to identify the market trend and also demand and supply. Analysis with dow theory, we need chart for 2 years. Once we have the chart, mark the tops and bottoms, then mark the higher top, higher bottom, lower top and lower bottoms. Then, look for the pattern HB, HT with volume high compare to previous bullish pattern to take long position. Similarly, look for LT, LB with high volume to take short position