as through sales to individual customers, returns to product vendors, or liquidations, and expected recoverable values of each disposition category. Based on this evaluation, we adjust the carrying amount of our inventories to lower of cost or market value. 

We provide fulfillment-related services in connection with certain of our agreements. In those arrangements, as well as other product sales by other sellers, the seller maintains ownership of the related products. As such, these amounts are not included in our consolidated balance sheets. 

Internal-Use Software and Website Development 

Included in fixed assets is the capitalized cost of internal-use software and website development, including software used to upgrade and enhance our websites and processes supporting our business. As required by Statement of Position (SOP) 98-1, “Accounting for the Costs of Computer Software Developed or Obtained for Internal Use,” we capitalize costs incurred during the application development stage of internal-use software and amortize these costs over the estimated useful life of two years. Costs incurred related to design or maintenance of internal-use software are expensed as incurred. 

Currency Effect on Intercompany Balances 

Gains and losses arising from intercompany foreign currency transactions are included in net income. 

Stock-Based Compensation 

We measure compensation cost for stock awards at fair value and recognize compensation over the service period for awards expected to vest. The fair value of restricted stock and restricted stock units is determined based on the number of shares granted and the quoted price of our common stock. Since we primarily issue restricted stock units to our employees, the complexity of valuation issues for stock compensation is greatly reduced. The estimation of stock awards that will ultimately vest requires judgment, and to the extent actual results or updated estimates differ from our current estimates, such amounts will be recorded as a cumulative adjustment in the period estimates are revised. We consider many factors when estimating expected forfeitures, including types of awards, employee class, and historical experience. Actual results and future estimates may differ substantially from our current estimates. 

We utilize the accelerated method, rather than a straight-line method, for recognizing compensation expense. Under this method, over 50% of the compensation cost would be expensed in the first year of a four-year vesting term. The accelerated method also adds a level of complexity in estimating forfeitures. If forfeited early in the life of an award, the forfeited amount is much greater under an accelerated method than under a straight-line method. 

Income Taxes 

We are subject to income taxes in both the U.S. and numerous foreign jurisdictions. Significant judgment is required in evaluating our tax positions and determining our provision for income taxes. During the ordinary course of business, there are many transactions and calculations for which the ultimate tax determination is uncertain. We establish reserves for tax-related uncertainties based on estimates of whether, and the