Sales 

Sales increased 41%, 40%, and 28% in 2011, 2010, and 2009. Changes in currency exchange rates positively (negatively) affected net sales by $1.1 billion, $(86) million, and $(182) million for 2011, 2010, and 2009. For a discussion of the effect on sales growth of exchange rates, see “Effect of Exchange Rates” below. 

The North America sales growth rate was 43%, 46%, and 25% in 2011, 2010, and 2009. The sales growth in each year primarily reflects increased unit sales. Increased unit sales were driven largely by our continued efforts to reduce prices for our customers, including from our shipping offers, by a larger base of sales in faster growing categories such as electronics and other general merchandise, by increased in-stock inventory availability, and by increased selection of product offerings. Additionally, North America sales growth reflects increased AWS activity. 

The International sales growth rate was 38%, 33%, and 31% in 2011, 2010, and 2009. The sales growth in each year primarily reflects increased unit sales. Increased unit sales were driven largely by our continued efforts to reduce prices for our customers, including from our shipping offers, by a larger base of sales in faster growing categories such as electronics and other general merchandise, by increased in-stock inventory availability, and by increased selection of product offerings. Additionally, changes in currency exchange rates positively (negatively) affected International net sales by $1.1 billion, $(107) million, and $(174) million in 2011, 2010, and 2009. We expect that, over time, our International segment will represent 50% or more of our consolidated net sales. 

Supplemental Information 

We expect our net cost of shipping to continue to increase to the extent our customers accept and use our shipping offers at an increasing rate; to the extent our product mix shifts to the electronics and other general merchandise category; to the extent we reduce shipping rates; to the extent we use more expensive shipping methods; and to the extent we offer additional services. We seek to mitigate costs of shipping over time in part through achieving higher sales volumes, negotiating better terms with our suppliers, and achieving better operating efficiencies. We believe that offering low prices to our customers is fundamental to our future success, and one way we offer lower prices is through shipping offers. 

Operating Expenses 

Operating expenses without stock-based compensation are non-GAAP financial measures. See “Non-GAAP Financial Measures” and Item 8 of Part I, “Financial Statements and Supplementary Data—Note 1—Description of Business and Accounting Policies—Stock-Based Compensation.” 

Cost of Sales 

Cost of sales consists of the purchase price of consumer products and digital content where we are the seller of record, inbound and outbound shipping charges, and packaging supplies. Shipping charges to receive products from our suppliers are included in our inventory, and recognized as cost of sales upon sale of products to our customers. 

The increase in cost of sales in absolute dollars in 2011, 2010, and 2009 compared to the comparable prior