Revenue Recognition

        Our revenue is principally derived from advertising services and subscription fees. We recognize revenue when: (1) persuasive evidence exists of an arrangement with the customer reflecting the terms and conditions under which products or services will be provided; (2) delivery has occurred or services have been provided; (3) the fee is fixed or determinable; and (4) collection is reasonably assured. For all revenue transactions, we consider a signed agreement, a binding insertion order or other similar documentation to be persuasive evidence of an arrangement.

        Advertising revenue. We generate advertising revenue primarily from audio, display and video advertising. We generate the majority of our advertising revenue through the delivery of advertising impressions sold on a cost per thousand, or CPM, basis. In determining whether an arrangement exists, we ensure that a binding arrangement, such as an insertion order or a fully executed customer-specific agreement, is in place. We generally recognize revenue based on delivery information from our campaign trafficking systems.

        We also generate advertising revenue pursuant to arrangements with advertising agencies and brokers. Under these arrangements, we provide the agencies and brokers the ability to sell advertising inventory on our service directly to advertisers. We report this revenue net of amounts due to agencies and brokers because we are not the primary obligor under these arrangements, we do not set the pricing and do not establish or maintain the relationship with the advertisers.

        Subscription and other revenue. We generate subscription revenue through the sale of a premium version of Pandora internet radio, or Pandora One. Subscription revenue derived from direct sales to listeners is recognized on a straight-line basis over the duration of the subscription period. Subscription revenue derived from sales through some mobile operating systems may be subject to refund or cancellation terms which may affect the timing or amount of the subscription revenue recognition. When refund rights exist, we recognize revenue when the service has been provided and the rights lapse or when sufficient transaction history has been developed to estimate a reserve.

        Deferred revenue. Our deferred revenue consists principally of both prepaid but unrecognized subscription revenue and advertising fees received or billed in advance of the delivery or completion of the delivery of services. Deferred revenue is recognized as revenue when the services are provided and all other revenue recognition criteria have been met. When refund rights exist, we recognize revenue when the rights lapse or when sufficient transaction history has been developed to estimate a reserve. As of December 31, 2013, we had deferred all revenue subject to certain refund rights totaling approximately $14.2 million, as we do not currently have sufficient history to estimate a reserve.

        Multiple-element arrangements. We enter into arrangements with customers to sell advertising packages that include different media placements or ad services that are delivered at the same time, or within close proximity of one another. We recognize the relative fair value of the media placements or ad services as they are delivered assuming all other revenue recognition criteria are met.

        We allocate arrangement consideration in multiple-deliverable revenue arrangements at the inception of an arrangement to all deliverables or those packages in which all components of the package are delivered at the same time, based on the relative selling price method in accordance with the selling price hierarchy, which includes: (1) vendor-specific objective evidence ("VSOE") if available; (2) third-party evidence ("TPE") if VSOE is not available; and (3) best estimate of selling price ("BESP") if neither VSOE nor TPE is available.

        VSOE. We determine VSOE based on our historical pricing and discounting practices for the specific product or service when sold separately. In determining VSOE, we require that a substantial majority of the selling prices for these services fall within a reasonably narrow pricing range. We have not historically priced our advertising products within a narrow range. As a result, we have not been able to establish VSOE for any of our advertising products.

        TPE. When VSOE cannot be established for deliverables in multiple element arrangements, we apply judgment with respect to whether it can establish a selling price based on TPE. TPE is determined based on competitor prices for similar deliverables when sold separately. Generally, our go-to-market strategy differs from that of our peers and our offerings contain a significant level of differentiation such that the comparable pricing of services cannot be obtained. Furthermore, we are unable to reliably determine what similar competitor services' selling prices are on a stand-alone basis. As a result, we have not been able to establish selling price based on TPE.

        BESP. When we are unable to establish selling price using VSOE or TPE, we use BESP in our allocation of arrangement consideration. The objective of BESP is to determine the price at which we would transact a sale if the service were sold on a stand-alone basis. BESP is generally used to allocate the selling price to deliverables in our multiple element arrangements. We determine BESP for deliverables by considering multiple factors including, but not limited to, prices we charge for similar offerings, market conditions, competitive landscape and pricing practices. We limit the amount of allocable arrangement consideration to amounts that are fixed or determinable and that are not contingent on future performance or future deliverables. We regularly review BESP. Changes in assumptions or judgments or changes to the elements in the arrangement may cause an increase or decrease in the amount of revenue that we report in a particular period.

Cash, Cash Equivalents and Investments

        We classify our highly liquid investments with maturities of three months or less at the date of purchase as cash equivalents. Our investments consist of commercial paper, corporate debt securities and U.S. government and government agency debt securities. These investments are classified as available-for-sale securities and are carried at fair value with the unrealized gains and losses reported as a component of stockholders' equity. Management determines the appropriate classification of our investments at the time of purchase and reevaluates the available-for-sale designations as of each balance sheet date. We classify our investments as either short-term or long-term based on each instrument's underlying contractual maturity date. Investments with maturities of less than twelve months are classified as short-term and those with maturities greater than twelve months are classified as long-term. The cost of investments sold is based upon the specific identification method.

Property and Equipment

        Property and equipment is recorded at cost, less accumulated depreciation and amortization. Depreciation is computed using the straight-line method based on the estimated useful lives of the assets, which range from three to five years. Leasehold improvements are amortized over the shorter of the lease term or expected useful lives of the improvements.

        Property and equipment is reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Recoverability of these assets is measured by a comparison of the carrying amounts to the future undiscounted cash flows the assets are expected to generate. If property and equipment are considered to be impaired, the impairment to be recognized equals the amount by which the carrying value of the asset exceeds its fair market value.

        Costs incurred to develop software for internal use are required to be capitalized and amortized over the estimated useful life of the asset if certain criteria are met. Costs related to preliminary project activities and post implementation activities are expensed as incurred. We evaluate the costs incurred during the application development stage of website development to determine whether the costs meet the criteria for capitalization. As of January 31, 2013 and December 31, 2013, we had approximately $1.1 million and $1.5 million of capitalized internal use software and website development costs, net of accumulated amortization. These costs are being amortized over their three-year estimated useful lives. Internal use software and website development costs are included in property and equipment.

Stock-Based Compensation

        Stock-based payments made to employees, including grants of employee stock options and restricted stock, are recognized in the statements of operations based on their fair values. We recognize stock-based compensation for awards granted that are expected to vest, on a straight-line basis using the single-option attribution method over the service period of the award, which is generally four years. Because stock-based compensation expenses recognized in the statements of operations are based on awards ultimately expected to vest, they have been reduced for estimated forfeitures. Forfeitures are required to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The forfeiture rates used for valuing stock-based compensation payments were estimated based on historical experience. We generally estimate the fair value of employee stock options using the Black-Scholes valuation model. The determination of the fair value of a stock-based award is affected by the deemed fair value of the underlying stock price on the grant date, as well as other assumptions including the risk-free interest rate, the estimated volatility of our stock price over the term of the award, the estimated period of time that we expect employees to hold their stock options and the expected dividend rate.

        We have elected to use the "with and without" approach as described in Accounting Standards Codification 740 Tax Provisions in determining the order in which tax attributes are utilized. As a result, we will only recognize a tax benefit from stock-based awards in additional paid-in capital if an incremental tax benefit is realized after all other tax attributes currently available to us have been utilized. In addition, we have elected to account for the indirect effects of stock-based awards on other tax attributes, such as the research tax credit, through the statement of operations.

Cost of Revenue—Other

        Cost of revenue—Other consists primarily of hosting and infrastructure costs and the employee-related costs associated with supporting those functions. Hosting costs consist of content streaming, maintaining our internet radio service and creating and serving advertisements through third-party ad servers. We make payments to third-party ad servers in the period in which the advertising impressions are delivered or click-through actions occur, and accordingly, we record this as a cost of revenue in the related period.

Sales and Marketing

        Sales and marketing consists primarily of employee-related costs, including salaries, commissions and benefits related to employees in sales, sales support and marketing departments. In addition, sales and marketing expenses include transaction processing fees for subscription purchases on mobile platforms, external sales and marketing expenses such as third-party marketing, branding, advertising and public relations expenses, facilities-related expenses, infrastructure costs and credit card fees.

Income Taxes

        We account for our income taxes using the asset and liability method, under which deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted statutory income tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce net deferred tax assets to the amount expected to be realized.

        We recognize a tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such positions are then measured based on the largest benefit that has a greater than 50% likelihood of being realized upon settlement. We will recognize interest and penalties related to unrecognized tax benefits in the income tax provision in the accompanying statement of operations.

        We calculate the current and deferred income tax provision based on estimates and assumptions that could differ from the actual results reflected in income tax returns filed in subsequent years. Adjustments based on filed income tax returns are recorded when identified. The amount of income taxes paid is subject to examination by U.S. federal, state and international tax authorities. The estimate of the potential outcome of any uncertain tax issue is subject to management's assessment of relevant risks, facts and circumstances existing at that time. To the extent that the assessment of such tax positions change, the change in estimate is recorded in the period in which the determination is made.