Trend lines are drawn on charts to help predict the general direction of price.It also help to determine good entry and exit point.they also help to see the reversals.
A line that is drawn over pivot highs or under pivot lows to show the prevailing direction of price. Trend lines are a visual representation of support and resistance .While the science of using trendlines is often not exact, it gives you an idea of the approximate future actions of a trending currency pair. Trendlines are a basic part of technical analysis.