Dow theory is important for long-term trading. It helps buyers decide when to buy and sell based on study of market behavior over a long period.
In Dow theory, one must identify trends by studying tops and bottoms created in line charts. Support and resistance help assess at which position there are many buyers and sellers. When analyzed along with volume, it can indicate in which direction the market is likely to move. Of course, one must set entry and exit points keeping minimal risk in mind.