1. A Line is a mark on a surface that usually describes a shape and is sometimes called an outline.
2. A Shape is flat and two dimensional with no form or thickness. Shapes are organized in terms of positive/negative, geometric and organic.
3. Texture is surface quality either tactile or visual.
4. Form is the illusion of 3-dimensional shape with volume and thickness. It is an illusion of 3 dimensions created by the application of value using shading techniques.
5. Value is the degree of light and dark in a design.
6. Color refers to hues, the color wheel and the properties of hue; intensity, temperature, value and saturation.
7. Emphasis is an area that first attracts attention in a composition.
8. Balance is a feeling of visual equality in shape, form, value, color, etc.
9. Contrast offers some change in value creating a visual discord in a composition.
10. Movement is a visual flow through the composition.
11.Rhythm is repetition and movement in which some elements repeat regularly. Like music, rhythms can be loud, soft, fast or slow.
12. 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. Some variety is good; too much destroys unity. Variety without repetition is weak.
13.Size refers to variations in the proportions of objects, lines or shapes. There is a variation of sizes in objects either real or imagined.
14.Space-refers to the application of linear or atmospheric perspective, overlap, scale change, atmospheric perspective and other techniques to create the illusion of fore/mid/background. Space can be flat and asserted or deep and illusionary.
15.Unity 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 rather than arbitrarily applying one geometric shape. (Notice how similar Harmony is to Unity - some sources list both terms) Unity refers to consistency in the elements and principles but also in techniques, processes and approaches.
16.Aesthetic- Concerned with beauty or the appreciation of beauty; Of pleasing appearance.
17. Asymmetry- Symmetry in which both halves of a composition are not identical. Also referred to as informal balance.
18.Gestalt-The principle that maintains that the human eye sees objects in their entirety before perceiving their individual parts.
19.Pattern- A repeated decorative design.
20.Radial Symmetry- Symmetry about a central axis.