1) EBITDA is the difference (X) between what customers are willing to pay for the products/services of a firm and the costs of providing such products/services before costs associated with reinvestment, financing, and taxes. One can say a) X is the true economic profit, or b) X is the new "earned " cash, or c) X is value-add by the firm. 2) Business has no value unless EBITDA is positive or projected to be positive. 3) EBITDA is cash, not cash flow. 4) Positive EBITDA does not guarantee positive cash flow. 5) MOST IMPORTANT, why we use EBITDA: EBITDA is the only profit measure that is the same between a buyer and seller on closing date/time.

Depreciation is mainly added back as a non cash item. The actual capex spend is then factored in subsequently as you build up from EBITDA to free cash to the firm/equity