technology and content so we may continue to enhance the customer experience and improve our process efficiency through rapid technology developments while operating at an ever increasing scale. Our technology and content investment and capital spending projects often support a variety of product and service offerings due to geographic expansion and the cross-functionality of our systems and operations. We expect spending in technology and content to increase over time as we continue to add employees and technology infrastructure. The increase in technology and content costs in absolute dollars in 2015 , 2014 , and 2013 , compared to comparable prior year periods, is primarily due to increased spending on technology infrastructure principally allocated to our AWS segment, and an increase in payroll and related costs associated with expanding our products and services. 

Technology infrastructure costs consist of servers, networking equipment, and data center related depreciation, rent, utilities, and payroll expenses. These costs are allocated to segments based on usage. In 2015 , 2014 , and 2013 , we expanded our technology infrastructure principally by increasing our capacity for AWS service offerings globally, compared to the comparable prior year periods. Additionally, the costs associated with operating and maintaining our expanded infrastructure have increased over time, corresponding with increased usage. We expect these trends to continue over time as we invest in technology infrastructure to support increased usage. 

The increase in payroll and related costs is primarily due to the expansion of new and existing product categories and service offerings, including AWS, and initiatives to expand our ecosystem of products and services. 

For 2015 , 2014 , and 2013 , we capitalized $642 million (including $114 million of stock-based compensation), $641 million (including $104 million of stock-based compensation), and $581 million (including $87 million of stock-based compensation) of costs associated with internal-use software and website development. Amortization of previously capitalized amounts was $635 million , $559 million , and $451 million for 2015 , 2014 , and 2013 . 

General and Administrative 

The increase in general and administrative costs in absolute dollars in 2015 , compared to the comparable prior year period, is primarily due to increases in payroll and related expenses. The increase in general and administrative costs in absolute dollars in 2014 , compared to the comparable prior year period, is primarily due to increases in payroll and related expenses and professional service fees. 

Stock-Based Compensation 

Stock-based compensation was $2.1 billion , $1.5 billion , and $1.1 billion during 2015 , 2014 , and 2013 . The increase in 2015 , 2014 , and 2013 , compared to the comparable prior year periods, is primarily due to an increase in the number of stock-based compensation awards granted to existing and new employees. 

Other Operating Expense (Income) 

Other operating expense (income), net was $171 million , $133 million , and $114 million during 2015 , 2014 , and 2013 , and was primarily related to the