A trend line is a straight line that connects at least two points and continues to serve as a support or resistance line in the future. By connecting significant lows in an upward trend and significant highs in a downward trend, trend lines provide dynamic resistance. In this context, dynamic resistance denotes that the price of the support or resistance varies over time. During an uptrend, for example, the level of support grows over time. The level of resistance decreases over time in a decline.