channels and certain third-party resellers. The Company has signed multi-year agreements with various cellular network carriers authorizing them to distribute and provide cellular network services for iPhones. These agreements are generally not exclusive with a specific carrier, except in the U.S., Germany, Spain, Ireland and certain other countries.

The Company’s iPods are sold through a significant number of distribution points to provide broad access. iPods can be purchased in certain department stores, member-only warehouse stores, large retail chains and specialty retail stores, as well as through the channels for Mac distribution listed above.

Critical Accounting Policies and Estimates

The preparation of financial statements and related disclosures in conformity with U.S. generally accepted accounting principles (“GAAP”) and the Company’s discussion and analysis of its financial condition and operating results require the Company’s management to make judgments, assumptions and estimates that affect the amounts reported in its consolidated financial statements and accompanying notes. Note 1, “Summary of Significant Accounting Policies” of Notes to Consolidated Financial Statements in this Form 10-K describes the significant accounting policies and methods used in the preparation of the Company’s consolidated financial statements. Management bases its estimates on historical experience and on various other assumptions it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates and such differences may be material.

Management believes the Company’s critical accounting policies and estimates are those related to revenue recognition, valuation of marketable securities, allowance for doubtful accounts, inventory valuation and inventory purchase commitments, warranty costs, income taxes, and legal and other contingencies. Management considers these policies critical because they are both important to the portrayal of the Company’s financial condition and operating results, and they require management to make judgments and estimates about inherently uncertain matters. The Company’s senior management has reviewed these critical accounting policies and related disclosures with the Audit and Finance Committee of the Company’s Board of Directors.

Revenue Recognition

Net sales consist primarily of revenue from the sale of hardware, software, third-party digital content and applications, peripherals, and service and support contracts. The Company recognizes revenue for software products (operating system software and applications software), or any product that is considered to be software-related, in accordance with industry specific accounting guidance for software and software related transactions (e.g., Mac computers, iPhones and iPod portable digital music and video players). For products that are not software or software-related, (e.g., third-party digital content sold on the iTunes Store and certain Mac, iPhone and iPod supplies and accessories), the Company recognizes revenue pursuant to