"Principles of design
Unity and Variety the degree of agreement existing among the ements in a design. Unity means that a congruity or arrangement exists among the elements in a design; they look as though they belong together, as though some visual connection beyond mere chance has caused them to come together. Another term for the same idea is harmony. Variety is variation on a visual theme causing contrast in a design.
Emphasis and Focal Point a compositional devise emphasizing a certain area or object to draw attention to the piece and to encourage closer scrutiny of the work. It is given to an area within the design because that area is meant to be seen or is more important when compared to other elements of the design. (Contrast is sometimes included as a principle of design and is similar to emphasis and focal point in that one may use contract to achieve emphasis)
Scale and Proportion are related terms in that both basically refer to size. Scale is essentially another word for size, and proportion refers to relative size-measured against other elements or against a mental norm or standard.
Balance is the distribution of visual weight of design elements within a composition. The equilibrium of opposing or interacting forces in a pictorial composition.
Rhythm is based on the repetition of recurrent motifs. It is the movement of variation characterized by the regular recurrence or alternation of different quantities or conditions. In simpler word, its just like pattern and shows that the design has a 'beat' or 'flow' going with it.
Elements of Design
Line is a visual element of length and can be created by setting a point in motion. Line defines the position and direction of the design. It can define shape, convey mood, feeling, and define space.
Shape and Volume is a visually perceived area created either by an enclosed line or by color or value changes defining the outer edge. A shape can also be called a form. It is something distinguished from its surroundings by its outline within your design. Volume is the appearance of height, width, and depth of form.
Texture and Pattern texture refers to the surface quality of an object that appeals to touch or tactile sense. Pattern is the repetition of visual elements or a module in a regular and anticipated sequence. (Depending on inter-pretation is sometimes considered a principle because it may be used to organize elements in a design)
Illusion of Space gives the illusion of 3D space on a 2D surface.
Illusion of Motion the suggestion of change or movement in 2D or 3D art.(Depending on interpretation motion is sometimes considered a principle)
Value is a measure of relative lightness or darkness of a color or tone of gray. An area's value is its relative lightness or darkness in any given context. Simply the artistic term for light and dark.
Color is a property of light, not an object itself. It is the way an object absorbs or reflects light."