This book presents both qualitative and quantitative approaches to cloud reliability measurements, together with specific case studies to reflect the real-time reliability applications. Traditional software reliability models cannot be used for cloud reliability evaluation due to the changes in the development architecture and delivery designs. The customer–vendor relationship mostly comes to a close with traditional software installations, whereas a SaaS subscription is just a start of the customer–vendor relationship. Reliability of cloud services is normally presented in terms of percentage, such as 99.9% or 99.99%. However, this type of reliability measurement provides confidence only in the service availability feature and may cover all the quality attributes of the product. The book offers a comprehensive review of the reliability models suitable for different services and deployments to help readers identify the appropriate cloud products for individual business needs. It also helps developers understand customer expectations and, most importantly, helps vendors to improve their service and support. As such it is a valuable resource for cloud customers, developers, vendors and the researchers.