Let's go back to our earlier discussion of the evolution of the video for the Web. A key link in the chain was the development of powerful, effective compression for web video. It might be helpful to explain very briefly how this works.
Video animation—whether digital or old school analog (like films)—is presented in frames. The more frames displayed per second, the smoother the animation.
Video compression reduces the size of a digital video not by reducing the number of frames, but by rationalizing the way frame data is saved. Say, for example, that you have a video of a person speaking against a background. It might well be the case that the background does not change throughout the video. Video compression software compresses the digital data necessary to present that video by organizing the data used to depict the background in such a way that it does not have to be repeated for each frame of the video.