The elements and principles of art and design are the foundation of the language we use to talk about art.
The principles of art represent how the artist uses the elements of art to create an effect and to help convey the artist's intent. The principles of art and design are:
Balance refers to the visual weight of the elements of the composition. It is a sense that the painting feels stable and "feels right." Balance can be achieved in 3 different ways -
symmetry, asymmetry and radial symmetry.
Contrast is the difference between elements of art in a composition, such that each element is made stronger in relation to the other. Areas of contrast are among the first places that a viewer's eye is drawn.
Emphasis the artist creates an area of the composition that is visually dominant and commands the viewer's attention. This is often achieved by contrast.
Movement is the result of using the elements of art such that they move the viewer's eye around and within the image. A sense of movement can be created by diagonal or curvy lines, either real or implied, by edges, by the illusion of space, by repetition, by energetic mark-making.
Pattern is the uniform repetition of any of the elements of art or any combination thereof. Anything can be turned into a pattern through repetition. Some classic patterns are spirals, grids, weaves.
Rhythm is created by movement implied through the repetition of elements of art in a non-uniform but organized way. It is related to rhythm in music. Unlike pattern, which demands consistency, rhythm relies on variety.
Unity is when you want your painting to feel unified such that all the elements fit together comfortably. Too much unity creates monotony, too much variety creates chaos.