The methods, estimates, and judgments that we use in applying our accounting policies have a significant impact on the results that we report in our financial statements. Some of our accounting policies require us to make difficult and subjective judgments, often as a result of the need to make estimates regarding matters that are inherently uncertain. Our most critical accounting estimates include:

• the valuation of non-marketable equity investments and the determination of other-than-temporary impairments, which impact gains (losses) on equity method investments, net, or gains (losses) on other equity investments, net when we record impairments;
• the valuation of investments in debt instruments and the determination of other-than-temporary impairments, which impact our investment portfolio balance when we assess fair value, and interest and other, net when we record impairments of available-for-sale debt instruments;
• the assessment of recoverability of long-lived assets, which primarily impacts gross margin or operating expenses when we record asset impairments or accelerate their depreciation;
• the recognition and measurement of current and deferred income taxes (including the measurement of uncertain tax positions), which impact our provision for taxes; and
• the valuation of inventory, which impacts gross margin.

Below, we discuss these policies further, as well as the estimates and judgments involved. We also have other policies that we consider key accounting policies, such as those for revenue recognition, including the deferral of revenue on sales to distributors; however, these policies typically do not require us to make estimates or judgments that are difficult or subjective.