The document discusses the key concepts of Dow Theory, which was developed over 100 years ago but still provides a valid framework for analyzing stock market movements. Dow Theory identifies three types of market movements - primary trends (bull/bear markets lasting months-years), secondary movements (corrections within primary bull trends or reaction rallies within primary bear trends lasting weeks-months), and daily fluctuations (lasting hours-days). It also discusses some of the theory's underlying assumptions, such as that the primary trend cannot be manipulated and that all known information is reflected in stock prices.