Trend

An uptrend is a sequence of higher highs and higher lows; a downtrend is lower highs and lower lows; a range is neither, with highs stalling near a ceiling and lows bouncing off a floor.

The description is deliberately mechanical so that rules can be written around it. The moment that matters is a structural break — an uptrend printing a lower low removes the justification for the old bias without automatically justifying the opposite one.