Principals of Design: Rhythm, Balance, Emphasis/ Contrast, and Movement
Rhythm: How things move. You may see repetition, pattern, or a variation of different patterns.
Balance: In Art, balance can be describing the overall harmony of a picture. Balance may be used to comment about a work of Art's composition.
Emphasis/ Contrast: Make specific things stand out. This can be done using color, texture, pattern, and countless other ways. See below.
Movement: The Art does not have to be physichally move, but the term could be used to describe how your eyes move around the picture when viewing. For example, your eyes may follow a red line from left to right.