One technique of animated film is to draw directly onto the film stock, painting, exposing, or otherwise marking each frame. The technique is painstaking, early directors sometimes working for years on a short work. Or, in other cases, drafting in entire teams to accomplish the task.
The earliest surviving example of abstract film is "Film ist Rhythmus: Rhythmus 21". This short makes its point clear from the title. It reduces film to its simplest component, the rectangle of the frame itself, in order to explore how representations of this frame can move in time. The visual rhythm marks out space with form, and articulates time with successive motions. The function is similar to dance, and it would be appropriate to describe Richter's work as choreographic.
The following is "Filmstudie" (1926), originally silent. A good number of silent films that you will find online have added soundtracks. These have been created either by the uploader or some anonymous source. I recommend listening without sound at first, since this can skew your perception of the visuals quite dramatically.
