Management also uses adjusted operating income, adjusted operating margin, adjusted net (loss) income, and adjusted net (loss) income per diluted share, which eliminate the impact of certain items that management does not consider indicative of underlying operating performance. Management believes these non-GAAP financial measures provide management and investors with additional information that is helpful when evaluating underlying performance. EBITDA and Adjusted EBITDA exclude interest expense, income taxes and depreciation, depletion and amortization, each of which is an essential element of the company’s cost structure and cannot be eliminated. In addition, Adjusted EBITDA and Adjusted EBITDA margin exclude certain cash and non-cash items, including stock-based compensation, impairment charges and certain restructuring charges. The calculation of non-GAAP financial measures as used by management is set forth in the following tables.