The Principles of Design describe the use of the elements previously covered (Line, Shape, Form, Value, Texture). These Principles use the elements and aid in the overall composition. Principles include the following theories:
Balance - Asymmetry vs. Symmetry
Harmony vs. Chaos
Odd vs. Even
Repetition & Rhythm
Movement & Flow - Diagonals & Triangles
Emphasis - Scale & Proportion
Notice many of these terms are also used in other forms of art such as Literature and Music. Many Principles also complement other principles in achieving a compositional end goal. Let's briefly define these Principles and how they are used in Design.
Balance: That which renders visible qualities equally. There are visual representations, such as weight, that can be used to achieve balance. The equal distribution of visible attributes in design are often not symmetrical, yet still give the overall sense of evenness. Unity, Harmony and Chaos are all results of attributing balance or an imbalance to a design.
Unity: The state of being one; oneness. Unity can be accomplished through balance and symmetry. However, it can also happen visually through other means such as the unity of movement, repetition or patterns and textures.
Harmony vs. Chaos: (HARMONY)The just adaptation of parts to each other, in any system or composition of things intended to form a connected whole. (CHAOS) Confusion; disorder; a state in which the parts are undistinguished. These yin and yang principles are heavily impacted by the force content plays in overall design. The end result in either Harmony or Chaos is visually represented by the use of elements complimenting each other or a dissonant application.
Odd vs. Even: We don't need a definition of Odd and Even. When elements are represented an odd number of ways, it is, generally, more visually interesting than being represented an even number of ways. There is some science behind this concept that we cannot get to at this point (I am writing this before our live video deadline just a few minutes away).
Tension: The act of stretching or straining. Visually, tension strains the mind and eye. A certain degree of tension represented in design can have an appealing effect as it keeps the viewer interested, subconsciously trying to understand what is "different" about the visual stimulation they are observing. Tension is commonly accomplished when objects are just about to touch or are pulling away from each other, when an object is just entering the picture plane or just leaving the picture plane, as well as when two diagonals cross.
Rhythm & Repetition: (RHYTHM) Duly regulated by cadences, accents and quantities. (REPETITION) Iteration of the same act for the purpose of making a deeper impression on the audience. Repeating elements throughout a design establishes a rhythm and can accomplish a sense of unity. It can also be used to create movement and direct the eye.
Movement & Flow: A passing, progression, shaking, turning or flowing (MOVEMENT). To glide along smoothly, without harshness or asperity (FLOW). Diagonals, triangles, repeating or rhythmic elements create a sense of movement in design. The more unified and harmonious this principle is applied the more lasting visual impression of "flow" it leaves on the viewer.
Pattern: An original or model proposed for imitation; the archetype. Patterns can be visually literal, like unifying textures, or more subdued, maybe through matching rhythmic undertones.
Emphasis: A particular stress suited to convey its meaning in the best manner. Emphasis in design is organized based on the hierarchy of information. This means that the more important information proportionately occupies more visual space. Scale promotes the emphatic essence.
Alignment: Arrangement in a straight line, or in correct or appropriate relative positions. There are many different alignment choices and preferences, but this principle will affect movement and flow and create hidden lines and shapes.
You can find a great outline of some of most of these principles covered here.
Definitions come from here. .