Cloud Computing is actually a very simple concept. The ability to deliver software applications and other services via the Internet.Cloud computing is the same stuff you do with your computer, such as office tasks or storing files, except done online.The term 'cloud computing' comes from the visual image of a cloud of data that floats out on the Internet, and which can be accessed from anywhere there's an Internet connection, on any computing device.In this book describe the cloud model and comparison of conventional computing and cloud computing and describe the advantages of it.This book explain virtualization and cloud service and cost effect when we use cloud computing.