In today's world there is an ever-changing, ever-expanding set of demands on the delivery, usage, availability, and reach of content. This paper discusses this set of demands and how they provide both the motivation and requirements for files and their role as part of the toolset used by broadcasters and content providers. It also briefly considers a range of new service opportunities that can be provided using files. Finally, as a good example of a suitable file format, which is also already widely used, the International Organization for Standardization (ISO) base media file format is described. This shows how it suits, and can be extended to suit, the requirements outlined earlier.