This chapter contains a comprehensive summary and analysis of the latest 3^rd Generation Partnership Project (3GPP) specifications and also findings from several 5G Public-Private Partnership (5G PPP) research projects. It provides detailed information for each network domain, as well as for the support of slicing across different operator administrative domains. Technological specificities of each domain require addressing different key issues for the realization of the slicing concept. The chapter discusses a realistic end-to-end (E2E) example of network slicing. Several slice operation aspects such as slice selection and isolation, context transfer, slice orchestration and management are presented. It also provides additional details on a number of slice operational aspects such as slice selection, connectivity to multiple slices, inter-slice radio resource management (RRM) functions, and the overall management of network slices. Finally, the chapter summarizes the key findings and also lists the technical challenges that still remain open.