MBD revenue increased primarily reflecting sales of the 2010 Microsoft Office system, the $254 million Office Deferral during fiscal year 2010, and the subsequent recognition of the Office Deferral during fiscal year 2011. Business revenue increased $2.0 billion or 13%, reflecting licensing of the 2010 Microsoft Office system to transactional business customers, growth in multi-year volume licensing revenue, and a 10% increase in Microsoft Dynamics revenue. Consumer revenue increased $1.1 billion or 33%, approximately half of which was attributable to the launch of Office 2010 and half of which was attributable to the Office Deferral during fiscal year 2010 and subsequent recognition of the Office Deferral during fiscal year 2011. Excluding the impact associated with the Office Deferral, consumer revenue increased $620 million or 17% due to sales of the 2010 Microsoft Office system.
MBD operating income increased due mainly to revenue growth, offset in part by higher operating expenses. Cost of revenue increased $335 million or 26%, primarily driven by higher online costs and services. Sales and marketing expenses increased $97 million or 2%, primarily driven by an increase in corporate and cross-platform marketing activities. Research and development costs increased $79 million or 4%, primarily as a result of capitalization of certain Microsoft Office system software development costs in the prior year.