Gastalt

Rooted from the theory of Visual Perception meaning that people tend to put visual elements to one whole piece when certain characters are applied,gestalt is simply trenslated, " unified whole".
There are many principles in which the theory applies; the principle of similarity is when an object looks similar to one another, thus making the viewers believe it is one whole group or pattern. In this term, anonmally meanings that something is out of the similarity.
The principle of continuism is when the eye follows an object and move through another object.
Closure happens when an object is not complete, or is not completely enclosed. When people see enough information or character of an object, they unknowingly fill the missing places.
Proximity is the percievence of whole when the objects are put closely together, creating unity.
Figure and ground are much related principles. Figure is defined as shape, sillouette or form, whileas the ground is what surrounds it.

Source from : http://graphicdesign.spokanefalls.edu
The Gestalt Principles