Unity refers to the relationship among the elements that help them function together. This gives a sense of oneness to a visual image, and the
viewer will see the design firstly as a whole before taking note of the individual elements in the piece.
There are several ways to unify an image and to facilitate viewer understanding. The use of similar shapes, common patterns, and the use of space can all make or break the unity of an image.
Unity is so important in visual art because the eye of the viewer automatically seeks ways to unify the piece and to see it as a whole. This phenomenon is called Gestalt Theory, and it simply states that viewers look for a connection
between the elements. In order to know how to bring unity to your art, it is important to know how the mind groups elements.
Proximity is grouping elements by closeness. The closer elements are to each other in a work, the more likely the viewer will see them as a group. Proximity is perhaps the easiest way to achieve unity in art and design. Repetition is grouping by similarity. Patterns are excellent for unity because of their unyielding repetition. The more similar elements are to each other, the more likely the viewer is to group them in their minds.
Alignment is arranging the elements so that their edges are lined up. Look at these bookcases, for example. Your eye follows the same line across and around, causing the eye to group them together.
Continuation is when an element (such as a line, color, or curve) continues from one element to another so that the viewer’s eye will follow, and the mind will connect the elements.