Excel 2010 includes Trendline which is a great data visualization tool to show the trend of specified data range. There are three kinds of trendlines; Linear Trendline, Exponential Trendline, and Linear Forecast Trendline. This post covers how to apply trendlines over the chart.
For inserting trendlines in chart, select a chart and navigate to Chart Tools Layout tab, From Trendline options, select a required type.
It will instantly insert trendline of specified type.