This lecture will give an overview of some of the design principles and considerations necessary for the design of superconducting electrical machines. Starting with the basic operating principles and uses of some commonly-used electrical machines, the use of different forms and types of superconducting materials in electrical machines will be discussed. This discussion will include superconducting material requirements, some of the technical challenges faced and cryogenic cooling options. There have been a number of projects around the world that have demonstrated the technical feasibility of superconducting machines in various forms and some of these will be used as case studies. Finally, some commentary will be made on the future outlook of superconducting electrical machines.