A waterfall chart shows how the initial value of a variable increases or decreases to a final value based on a series of intermediate values that impact that variable. For example, the table below shows that the sales for a company at the end of 2007 was 7.98 million dollars. During 2008, Products A - H either increased in sales (positive number) or decreased in sales (negative number). These increases and decreases lead to the final sales in 2008. A waterfall chart is a picture of this. The example is based on the sales situation described above.