We provide investors with non-GAAP gross profit and gross margin, non-GAAP operating income and operating margin and non-GAAP net income because we believe it is important for investors to be able to closely monitor and understand changes in our ability to generate income from ongoing business operations. We believe these non-GAAP financial measures give investors an additional method to evaluate historical operating performance and identify trends, additional means of evaluating period-over-period operating performance and a method to facilitate certain comparisons of operating results to peer companies. We also believe that providing non-GAAP operating income and operating margin allows investors to assess the extent to which ongoing operations impact our overall financial performance. We further believe that providing non-GAAP net income and non-GAAP net income per share (diluted) allows investors to assess the overall financial performance of ongoing operations by eliminating the impact of certain financing decisions related to our convertible debt and certain tax items which may not occur in each period presented and which may represent non-cash items or gains or losses unrelated to our ongoing operations. We believe that disclosing these non-GAAP financial measures contributes to enhanced financial reporting transparency and provides investors with added clarity about complex financial performance measures.
We calculate non-GAAP gross profit by excluding from GAAP gross profit, stock compensation expense, restructuring-related charges and acquisition-related expenses. We calculate non-GAAP operating income by excluding from GAAP operating income, stock compensation expense, restructuring-related charges, acquisition-related expenses, litigation settlement gains and losses and certain deferred executive compensation. We calculate non-GAAP net income and net income per share (diluted) by excluding from GAAP net income and net income per share (diluted), stock compensation expense, restructuring-related charges, acquisition-related expenses, litigation settlement gains and losses, amortization of discount on convertible debt, and certain deferred executive compensation, as well as certain items related to the retirement of convertible debt, and certain tax items, which may not occur in all periods for which financial information is presented. We exclude the items identified above from the respective non-GAAP financial measure referenced above for the reasons set forth with respect to each such excluded item below: