The three most used services are: Software-as-a-Service (Saas), a software distribution and licensing model. It's usually on subscription basis and centrally hosted. An example is Dropbox, an on-demand storage solution Infrastructure-as-a-Service (IaaS), an infrastructure model by which computer resources are hosted Platform-as-a-Service (PaaS), a type of cloud computing model that delivers application infrastructure capabilities to be used by for instance developers to build an app