What is the difference between cash flow and free cash flow?

A corporation’s cash flow from operations is available from the first section of the statement of cash flows. Usually the calculation begins with the accrual accounting net income followed by adding back depreciation
expense and then adjusting for the changes in the balances of current assets and current liabilities.

Free cash flow is often defined as the cash flow from operations (or net cash flows from operating activities) minus the cash necessary for capital expenditures. Occasionally, dividends to stockholders are also deducted.