The book "Cloud Computing" presents the revised conference proceedings of the first International Conference on Cloud Computing, CloudCom 2009, which took place from December 1 to 4, 2009, in Beijing, China. It includes 42 full papers as well as four invited contributions, carefully selected from a total of 200 submissions. The topics covered are diverse, ranging from cloud and grid architectures to load balancing and optimal provisioning configurations, as well as virtualization technologies and middleware frameworks. Additionally, aspects such as Software as a Service (SaaS), Hardware as a Service (HaaS), data grids, semantic web, web services, security and risk management, fault tolerance, reliability, auditing, monitoring, scheduling, utility computing, high-performance computing, and peer-to-peer computing are addressed. This specialized book thus provides a comprehensive overview of the current developments and challenges in the field of cloud computing.