A trendline support is a line drawn by connecting at least two or more swing lows that lie along a downward or horizontal slope. It acts like a floor, showing where buyers consistently step in to accumulate shares, preventing prices from falling further. Each time price touches the trendline and bounces upward, it confirms the strength of that support zone. In this chart, prices tested the blue trendline support multiple times but failed to close below it — indicating strong demand around that area. When such support holds and price later shows a strong bullish candle (as seen on the right), it often signals renewed buying interest and can lead to a trend reversal or upward rally. In short: The more times a trendline support is respected, the more reliable it becomes. It helps traders identify low-risk entry points and stop-loss levels, making it a crucial element of price action trading.