{In former times, it was necessary to operate and maintain powerful personal computers to run applications. Nowadays, many "normal" users just use laptops, tablet PCs or smartphones. Their applications are powered by cloud systems in the background, which are operated in data centres at remote locations and being connected over the Internet. This presentation first introduces the basics of cloud computing: virtualisation, virtual machines, containers, and software as a service. A challenge of using cloud computing is to deploy services to cloud providers, in order to operate them in a cost-efficient way while providing the best application experience to the users. The vision of the Multi-Cloud Execution-Ware for Large-scale Optimised Data-Intensive Computing (MELODIC) project is to enable federated cloud computing for data-intensive applications. Furthermore, it provides the user with an easy-to-use, unified cloud environment, which hides the complexity of a multi-cloud. The second part of this presentation therefore provides an overview of the basic ideas and application use cases of MELODIC.}