income (expense), net was $(118) million, $(136) million, and $(80) million during 2014, 2013, and 2012. The primary component of other income (expense), net is related to foreign-currency gains (losses). 

Income Taxes 

Our effective tax rate is subject to significant variation due to several factors, including variability in our pre-tax and taxable income and loss and the mix of jurisdictions to which they relate, changes in how we do business, acquisitions (including integrations) and investments, audit-related developments, foreign currency gains (losses), changes in law, regulations, and administrative practices, and relative changes of expenses or losses for which tax benefits are not recognized. Additionally, our effective tax rate can be more or less volatile based on the amount of pre-tax income or loss. For example, the impact of discrete items and non-deductible expenses on our effective tax rate is greater when our pre-tax income is lower. 

We recorded a provision for income taxes of $167 million, $161 million, and $428 million in 2014, 2013, and 2012. Our provision for income taxes in 2014 was higher than in 2013 primarily due to the increased losses in certain foreign subsidiaries for which we may not realize a tax benefit and audit-related developments, partially offset by the favorable impact of earnings in lower tax rate jurisdictions. Losses for which we may not realize a related tax benefit reduce our pre-tax income without a corresponding reduction in our tax expense, and therefore increase our effective tax rate. We have recorded valuation allowances against the deferred tax assets associated with losses for which we may not realize a related tax benefit. Income earned in lower tax jurisdictions is primarily related to our European operations, which are headquartered in Luxembourg. 

In 2013, our provision for income taxes was lower than in 2012 primarily due to a decline in the proportion of our losses for which we may not realize a related tax benefit, the favorable impact of earnings in lower tax rate jurisdictions, and the retroactive extension in 2013 of the U.S. federal research and development credit to 2012. In 2013, we recognized tax benefits for a greater proportion of losses for which we may not realize a tax benefit, primarily due to losses of certain foreign subsidiaries, as compared to 2012. The favorable impact of earnings in lower tax rate jurisdictions was primarily related to our European operations. 

We have tax benefits relating to excess stock-based compensation deductions and accelerated depreciation deductions that are being utilized to reduce our U.S. taxable income. In December 2014, U.S. legislation was enacted providing a one year extension of accelerated depreciation deductions on qualifying property and the U.S. federal research and development credit through December 31, 2014. As of December 31, 2014 , our federal net operating loss carryforward was approximately $1.9 billion and we had approximately $443 million of federal tax credits potentially available to offset future tax liabilities. Our federal tax credits are primarily related to the U.S. federal research and development credit,