This book answers the following questions:  Why Cloud Computing?  What is Cloud Computing? How does Cloud Computing work?  What are its challenges and opportunities and how to address them?  What are the career opportunities in the Cloud Computing area?  What is Green Cloud Computing  What is Cloud Data Security Management Cloud computing is rage these days. "It's become the phrase du jour," says Gartner, senior analyst, Ben Pring. This book attempts to unravel the mystery behind this buzzword. The primary objective is to provide an introduction to the current practices of Cloud Computing, also known as the Internet as a platform. This book takes a cross-disciplinary approach covering topics in business, computer science, and information systems. Mainly focusing on cloud computing models, techniques, and architectures, this book provides knowledge and hands-on experience in designing and implementing cloud-based software systems. Topics included are advanced web technologies (AJAX and Mashup), distributed computing models and technologies (Hadoop and MapReduce), Infrastructure-as-a-Service (IaaS), Software as a Service (SaaS), Platform-as-a-Service (PaaS), virtualization, parallelization, security/privacy, and other issues in cloud computing. This book also explores the current challenges facing cloud computing. This book has deep theoretical foundations of Cloud Computing and associated topics and case studies. Cloud Computing is one of the upcoming and sought-after subjects in most IT companies. This subject will be useful to all professionals and B. Tech, MCA, M. Tech and MBA students. This edition has two new chapters that are most topical for current cloud implementation, namely:  Green Cloud Computing  Cloud Data Security Management