What is Emphasis in Design:
Emphasis in design provides the focal point for the piece. It is a way of making the element that is most important stand out in the design. Emphasis is sometimes called dominance.
Use of Emphasis in Design:
One of the biggest mistakes designers can make is trying to make everything in the design stand out. When everything has equal emphasis at best it can make the piece appear busy, and at worst the design will be boring and unappealing.
Instead, focus on creating a visual hierarchy in your designs. If you've worked to create a semantic flow to your HTML markup, that will be easier. Because your Web page will already have a hierarchy, all your design needs to do is put the emphasis on the correct elements - such as the H1 element for the most emphasis and so on.