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 and impairment of marketable securities, 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, digital content and applications, peripherals, and service and support contracts. The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred, the sales price is fixed or determinable, and collection is probable. Product is considered delivered to the customer once it has been shipped and title and risk of loss have been transferred. For most of the Company’s product sales, these criteria are met at the time the product is shipped. For online sales to individuals, for some sales to education customers in the U.S., and for certain other sales, the Company defers revenue until the customer receives the product because the Company retains a portion of the risk of loss on these sales during transit. The Company recognizes revenue from the sale of hardware products, software bundled with hardware that is essential to the functionality of the hardware, and third-party digital content sold on the iTunes Store in accordance with general revenue recognition accounting guidance. The Company recognizes revenue in accordance with industry specific software accounting guidance for the following types of sales transactions: (i) standalone sales of software products, (ii) sales of software upgrades and (iii) sales of software bundled with hardware not essential to the functionality of the hardware. 

For multi-element arrangements that include hardware products containing software essential to the hardware product’s functionality, undelivered software elements that relate to the hardware product’s essential software, and/or undelivered non-software services, the Company allocates revenue to all deliverables based on their relative selling prices. In such circumstances, the Company uses a hierarchy to determine the selling price to be used for allocating revenue to deliverables: (i) vendor-specific objective evidence of fair value (“VSOE”), (ii) third-party evidence of selling price (“TPE”) and (iii) best estimate of selling price (“ESP”). VSOE generally exists only when the Company sells the deliverable separately and is the price actually charged by the Company for that deliverable. ESPs reflect the Company’s best estimates of what the selling prices