Line
is a mark on a surface that usually describes a shape (such as in an "outline" or an edge. It can define a shape and imply texture. It can be thick or thin, smooth or nervous. Types can include straight, curved, zig-zag, wavy, etc. Lines can also be impli
Shape
is flat and two dimensional with no form or thickness. They are organized in terms of positive/negative, geometric and organic.
Texture
it is how something feels. It's surface quality can either be tactile or visual. It can be real or implied. It is the degree of roughness or smoothness in objects and compositions.
Form
refers to 3-D or it can be an illusion of 3-D created by the application of value using shading techniques
Value
is the degree of light and dark in a drawing. It is the contrast between black, white and all the tones in between. It can be used with color as well as black and white. Contrast is the range between lightest and darkest values.
Color
reflection of light and refers to hues and the properties of hue; intensity, temperature, value and saturation.
Emphasis
is an area that first attracts attention in a composition. This area is more important when compared to the other objects or elements in a composition
Balance
is a feeling of visual equality in shape, form, value, color, etc. Balance can be symmetrical, which is a mirror image that is evenly balanced or asymmetrical and un-evenly balanced
Unity/Harmony
brings together a composition with similar units. If your composition uses wavy lines and organic shapes you would stay with those types of lines and shapes
Contrast
offers some change in value creating a visual discord in a composition. It shows the difference between items and can be used as a background to bring objects out and forward in a design
Movement
is a visual flow through the composition
Rhythm
is repetition and movement in which some/all elements repeat regularly
Variety
is using different variations of an element in a composition. For example, circles and rectangles or straight and wavy lines or large leafs and small. Used without repetition it is weak.
Proportion (Size)
refers to variations in the proportions of objects, lines or shapes
Space
refers to the application of linear or atmospheric perspective, overlap, scale change, and other techniques to create the illusion of fore/mid/background. Space can be flat and asserted or deep and illusionary.