Cloud computing is a recent paradigm based around the notion of delivery of resources via a service model over the Internet. Despite being a new paradigm of computation, cloud computing owes its origins to a number of previous paradigms. The term cloud computing is well defined and no longer merits rigorous taxonomies to furnish a definition. Instead this survey paper considers the past, present and future of cloud computing. As an evolution of previous paradigms, we consider the predecessors to cloud computing and what significance they still hold to cloud services. Additionally we examine the technologies which comprise cloud computing and how the challenges and future developments of these technologies will influence the field. Finally we examine the challenges that limit the growth, application and development of cloud computing and suggest directions required to overcome these challenges in order to further the success of cloud computing.