A trend, in financial markets, is the prevailing direction of a price over a period of time. An uptrend is a sequence of higher highs and higher lows, a downtrend a sequence of lower highs and lower lows, and a sideways or ranging market shows neither. Trends are classified by duration. In the tradition of Dow theory, a primary trend lasts a year or more, a secondary trend runs for weeks or months against it, and minor trends last days. A long primary uptrend is a bull market.
Identifying the trend is the first task of technical analysis. Common tools are trendlines drawn through successive lows or highs, a moving average whose slope and position relative to price show direction, and indicators of trend strength such as the average directional index. Trend following strategies trade in the direction of an established trend. Apparent trends also arise by chance in random price series.