A measure of financial performance that expresses the net amount of cash that is generated for the firm, consisting of expenses, taxes and changes in net working capital and investments.
Calculated as: 
Investopedia Says:
This is a measurement of a company's profitability after all expenses and reinvestments. It's one of the many benchmarks used to compare and analyze financial health.
A positive value would indicate that the firm has cash left after expenses. A negative value, on the other hand, would indicate that the firm has not generated enough revenue to cover its costs and investment activities. In that instance, an investor should dig deeper to assess why this is happening - it could be a sign that the company may have some deeper problems.
Related Links:
Learn how and why investors are using cash flow-based analysis to make judgments about company performance. Taking Stock Of Discounted Cash Flow
Free cash flow is a great gauge of corporate health, but it's not immune to accounting trickery. Free Cash Flow: Free, But Not Always Easy
This measure may have its benefits, but it can also present earnings through rose-colored glasses. A Clear Look At EBITDA
Tune out the accounting noise and see whether a company is generating the stuff it needs to sustain itself. The Essentials Of Cash Flow
Learn how the CFS relates to the balance sheet and income statement as a part of a company's financial reports. What Is A Cash Flow Statement?
