InterCloud is a utility-oriented federation of cloud computing environments designed to scale application services and achieve reasonable Quality of Service (QoS) levels. The paper presents the vision, challenges, and architectural elements of InterCloud for federating cloud computing environments. The proposed InterCloud environment supports scaling of applications across multiple vendor clouds. The authors validated their approach using the CloudSim toolkit and found that federated cloud computing models offer significant performance gains in terms of response time and cost savings under dynamic workload scenarios. Cloud computing has evolved from a service provisioning model to a dynamic infrastructure that allows users to access and deploy applications from anywhere in the world on demand. This model has been referred to as utility computing or cloud computing. Cloud computing delivers infrastructure, platform, and software as services, which are made available as subscription-based services in a pay-as-you-go model to consumers. These services are respectively referred to as Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). Cloud computing aims to power the next generation data centers by architecting them as a network of virtual services (hardware, database, user-interface, application logic) so that users are able to access and deploy applications from anywhere in the world on demand at competitive costs depending on users QoS (Quality of Service) requirements. Developers with innovative ideas for new Internet services no longer require large capital outlays in hardware to deploy their service or human expense to operate it. The business potential of Cloud computing is recognized by several market research firms including IDC, which reports that worldwide spending on Cloud services will grow from $16 billion by 2008 to $42 billion in 2012. Furthermore, many applications making use of these utility-oriented computing systems such as clouds emerge simply as catalysts or market makers that bring buyers and sellers together. This creates several trillion dollars of worth to the utility/pervasive computing industry. The paper discusses the challenges and requirements of application scaling and cloud infrastructure, particularly in the context of social networking web applications. These applications serve dynamic content to millions of users, whose access and interaction patterns are hard to predict. In several situations load spikes can take place, for instance, whenever new system features become popular or a new plugin application is deployed. As these social networks are organized in communities of highly interacting users distributed all over the world, load spikes can take place at different locations at any time. In order to handle unpredictable seasonal and geographical changes in system workload, an automatic scaling scheme is paramount to keep QoS and resource consumption at suitable levels. The paper also discusses the challenges of federated cloud infrastructures for elastic applications. Cloud infrastructure providers have established data centers in multiple geographical locations to provide redundancy and ensure reliability in case of site failures. However, currently they expect their Cloud customers to express a preference about the location where they want their application services to be hosted and don't provide seamless/automatic mechanisms for scaling their hosted services across multipleInterCloud is a utility-oriented federation of cloud computing environments designed to scale application services and achieve reasonable Quality of Service (QoS) levels. The paper presents the vision, challenges, and architectural elements of InterCloud for federating cloud computing environments. The proposed InterCloud environment supports scaling of applications across multiple vendor clouds. The authors validated their approach using the CloudSim toolkit and found that federated cloud computing models offer significant performance gains in terms of response time and cost savings under dynamic workload scenarios. Cloud computing has evolved from a service provisioning model to a dynamic infrastructure that allows users to access and deploy applications from anywhere in the world on demand. This model has been referred to as utility computing or cloud computing. Cloud computing delivers infrastructure, platform, and software as services, which are made available as subscription-based services in a pay-as-you-go model to consumers. These services are respectively referred to as Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). Cloud computing aims to power the next generation data centers by architecting them as a network of virtual services (hardware, database, user-interface, application logic) so that users are able to access and deploy applications from anywhere in the world on demand at competitive costs depending on users QoS (Quality of Service) requirements. Developers with innovative ideas for new Internet services no longer require large capital outlays in hardware to deploy their service or human expense to operate it. The business potential of Cloud computing is recognized by several market research firms including IDC, which reports that worldwide spending on Cloud services will grow from $16 billion by 2008 to $42 billion in 2012. Furthermore, many applications making use of these utility-oriented computing systems such as clouds emerge simply as catalysts or market makers that bring buyers and sellers together. This creates several trillion dollars of worth to the utility/pervasive computing industry. The paper discusses the challenges and requirements of application scaling and cloud infrastructure, particularly in the context of social networking web applications. These applications serve dynamic content to millions of users, whose access and interaction patterns are hard to predict. In several situations load spikes can take place, for instance, whenever new system features become popular or a new plugin application is deployed. As these social networks are organized in communities of highly interacting users distributed all over the world, load spikes can take place at different locations at any time. In order to handle unpredictable seasonal and geographical changes in system workload, an automatic scaling scheme is paramount to keep QoS and resource consumption at suitable levels. The paper also discusses the challenges of federated cloud infrastructures for elastic applications. Cloud infrastructure providers have established data centers in multiple geographical locations to provide redundancy and ensure reliability in case of site failures. However, currently they expect their Cloud customers to express a preference about the location where they want their application services to be hosted and don't provide seamless/automatic mechanisms for scaling their hosted services across multiple