$IDFCFIRSTB A trendline support zone is an area where the price repeatedly finds buying interest near an upward-sloping trendline during an uptrend. When the price declines toward this zone and bounces back, it indicates that buyers are defending the trend and maintaining bullish momentum. Multiple successful rebounds from the trendline support zone strengthen its reliability, while a decisive breakdown below the zone may signal weakening bullish sentiment and a potential trend reversal.