Essentially lines, points and spaces ...
The drawing has many definitions, but as said by an old friend: "To understand something, firstly you need to know its meaning."
[ The Noun Drawing, 1913 Webster: The act or the art of representing any object by means of lines and shades; especially, such a representation when in one color, or in tints used not to represent the colors of natural objects, but for effect only, and produced with hard material such as pencil, chalk, etc.; delineation; also, the figure or representation drawn.]
I think it is an interesting, short and classical definition... and it is very useful to understand how the "draw drawings" concept has changed through the 20th century.