Trend line
A line through the extremes that shows the slope of the move.
A trend line is drawn through two or more extremes: lows in an uptrend, highs in a downtrend. Its job is description, not prediction — it makes the slope of the move and the pace the market keeps it at visible. While price respects the line the tendency is considered intact; a change of slope or a decisive break is a reason to review the scenario, not an automatic entry signal.