A line going for a walk - Drawing

Drawing, the art or technique of producing images on a surface, usually paper, by means of marks, usually of ink, graphite, chalk, charcoal, or crayon.

Line is the most basic element of the drawing. And in it's most basic definition, it's what separates one area of the drawing plane from the other. A single line will segment your piece of paper into "that area" and "this area". The more lines that are added, the more complex and numerous the separations become: light from dark, foreground from background, positive space from negative space. Line can be uniform and all one width, or to be more interesting, and to convey more information with a single line, a single line can be of varying widths.

Shape occurs when the first line is drawn. The most basic definition of shape is the white area on the paper. Shape is the information that is presented between two or more lines, or is the thing that is enclosed by line. Shape helps define the object that is depicted as much as the collection of lines that make up the object in the drawing. Incorrect use of shape will cause the drawing to "not look like what it's supposed to be."

Form is mathematical, precise, and can be named, as in the basic geometric forms: circle, square and triangle. A circle becomes a sphere in three dimensions, a square becomes a cube, a triangle becomes cone. Proportion is the size of one picture element in relation to the size of another. In other words Proportion is what dictates that, in humans, legs are longer than arms, the middle finger is longer than the pointer finger, and the nose is the same length as the width of the eye. If proportion is incorrect in a drawing it "doesn't look right". Perspective is the illusion that further away things appear smaller. To make something appear to be farther away from the viewer than the picture plane, draw it smaller than the object that is closer to the picture plane.

Value or light and shadow create depth and atmosphere in a drawing. In order to make a drawing look "realistic" you need shadow because in the real world everything has a shadow. If you draw something with only one width line and don't render shadow, your drawing is going to look flat, two dimensional, and unrealistic. Adding shadow automatically adds a small bit of perspective to the drawing because the shadow indicates that something is in front of and/or behind the object that would cause it to cast a shadow.

Space, refers to the distances or areas around, between, and within components of a piece. Space can be positive or negative, open or closed, shallow or deep, and two-dimensional or three-dimensional. Sometimes space isn't explicitly presented within a piece, but the illusion of it is. Space gives the viewer a reference for interpreting an artwork. For instance, you may draw one object larger than another to imply that it is closer to the viewer. Likewise, a piece of environmental art may be installed in a way that leads the viewer through space.

Negative and Positive Space - Art historians use the term positive space to refer to the subject of the piece itself—the flower vase in a painting or the structure of a sculpture. Negative space refers to the empty spaces the artist has created around, between, and within the subjects.

Quite often, we think of positive as being light and negative as being dark. This does not necessarily apply to every piece of art. For example, you might paint a black cup on a white canvas. We wouldn't necessarily call the cup negative because it is the subject: The black value is negative, but the space of the cup is positive.

*my readings from the internet