Balance is a form of equilibrium within a Web page or visual. Visuals on a Web page that are out of balance are disturbing to viewers. Formal balance refers to a situation in which the two halves of the visual are symmetrically arranged around the vertical center of the visual. Informal balance refers to an arrangement in which the elements are not symmetrically arranged, but still appear balanced and stable. Informal balance is more difficult to achieve, but can result in more interesting visuals.
Unity refers to the strength of the relationship between the elements of a visual.
The elements should be tied together into a single meaningful unit. To ensure unity in a visual, place the elements very close together, overlap the elements and use a border or a background shape. The homepage of your Web site is where you meet and greet your site visitors. The top vertical four inches are the most valuable real estate in your Web site. This area should be the densest area in your site.