The Tenkan-sen is a key component of the Ichimoku Kinko Hyo trading system, used in technical analysis to identify trends in financial markets. It is calculated by averaging the highest high and the lowest low over the last nine periods. This line helps traders determine short-term momentum and potential reversal points. In a chart, the Tenkan-sen appears as a line that reacts quickly to price changes, making it useful for spotting immediate market shifts. When the price is above the Tenkan-sen, it indicates a bullish trend, while a price below suggests a bearish trend.