Based on research on the development of streaming solutions across media forms and industries, this article traces the dynamics and dimensions of the notion of streaming. It theorizes streaming as an evolving concept, and argues against strict, set and limited definitions such as those suggested by Lotz and Herbert et al. A short substantive and industrial history of streaming is provided, recognizing its many manifestations and variations. Five key dimensions are identified, and trends and traits within each of them discussed: (1) professional versus user-generated streaming, (2) legal versus piracy streaming, (3) on-demand versus live streaming, (4) streaming on dedicated versus multi-feature platforms, and (5) niche versus general-audience streaming. The article concludes by pointing out how streaming is a concept that metaphorically unites media research across industries, practices, and media forms, encouraging more comparative research.