The Digital Twin (DT) is an emerging approach that promises to change the way products and systems are made and used. The DT is attracting increasing interest in the Internet of Things community for its potential applications. Despite the hype, this approach requires a more precise definition and characterization in terms of its properties in relationship to software architectures and their platform implementations, as well as a deeper analysis of its potential applications and actual feasibility in several industries. This paper investigates the basic properties that hold for a DT, sketches a software framework and presents two application scenarios. The paper also addresses the business impact of DT by discussing servitization capabilities.