Streams are Object Orientated. Each class of Stream has its own ~operations~ structure. It defines the methods that can be called for that class of stream Each instance of a given class share the same operations structure. Each instance has its own abstract data pointer to hold instance specific data (such as the underlying file/resource handles). To implement your own stream you need to define an operations structure and the methods that apply to your stream. The core methods are: %write()% - write data to the stream %read()% - read data from the stream %close()% - shutdown/release the stream %flush()% - ensure data is flushed to storage %seek()% - move to an offset within the stream