The principle that price trends exhibit the same volume-spread-close characteristics at every scale: a short-term trend on a weekly chart is an intermediate trend on a daily chart and a long-term trend on a five-minute chart. There is no fixed definition of short-term or long-term—these are relative descriptions that depend on the timeframe being observed. Within every major uptrend, there are intermediate reactions, and within every reaction, there are short-term rallies. Professional traders exploit this by trading counter-trend moves within the direction of the major trend.