A diagram is a symbolic representation of information using visualization techniques. Diagrams have been used since prehistoric times on walls of caves.
See Graphics below.
https://en.m.wikipedia.org/wiki/Diagram
HEIGHT 400
Wikipedia 
.
**Graphics** (from Ancient Greek γραφικός (graphikós) 'pertaining to drawing, painting, writing, etc.') are visual images or designs on some surface, such as a wall, canvas, screen, paper, or stone, to inform, illustrate, or entertain. In contemporary usage, it includes a pictorial representation of data, as in design and manufacture, in typesetting and the graphic arts, and in educational and recreational software. Images that are generated by a computer are called computer graphics.
https://en.m.wikipedia.org/wiki/Graphics
HEIGHT 400
Wikipedia