The concept of trend is absolutely essential to the technical approach to market analysis. All of the tools used by the chartist—support and resistance levels, price patterns, moving averages, trendlines, etc.—have the sole purpose of helping to measure the trend of the market for the purpose of participating in that trend. We often hear such familiar expressions as "always trade in the direction of the trend," "never buck the trend," or "the trend is your friend." So let's spend a little time to define what a trend is and classify it into a few categories.
In a general sense, the trend is simply the direction of the market, which way it's moving. But we need a more precise defi­nition with which to work. First of all, markets don't generally move in a straight line in any direction. Market moves are char­acterized by a series of zigzags. These zigzags resemble a series of successive waves with fairly obvious peaks and troughs. It is the direction of those peaks and troughs that constitutes market trend. Whether those peaks and troughs are moving up, down, or side‑ways tells us the trend of the market. An uptrend would be defined as a series of successively higher peaks and troughs; a downtrend is just the opposite, a series of declining peaks and troughs; hori­zontal peaks and troughs would identify a sideways price trend.