This Book is released to address the academic and research needs in cloud computing. Cloud computing has emerged as the distributed computing paradigm, that provides an enormous pool of shared computing resources like storage, memory, networks, applications, and processing power to the users. Based on the demand, they may provide and release the resources as they required by paying only for the number of resources they utilized. This book majorly concentrated on core concepts (i.e. security issue in cloud) and advanced research topics.