“Support and resistance” is one of the most widely used concepts in forex trading which implies that the movement of the price of a security will tend to stop and reverse at certain predetermined price levels.
When the forex market moves up and then pulls back, the highest point reached before it pulled back is now resistance.
As the market continues up again, the lowest point reached before it started back is now support. In this way, resistance and support are continually formed as the forex market oscillates over time. The reverse is true for the downtrend.
The support/resistance of an identified level, whether discovered with a trendline or through any other method, is deemed to be stronger the more times that the price has historically been unable to move beyond it. Many technical traders will use their identified support and resistance levels to choose strategic entry/exit prices because these areas often represent the prices that are the most influential to an asset's direction.