By making parts of your text bold, you are creating emphasis
on the words that are more bold.
Weight refers to the perceived mass created by the typeface's stroke and counters. Using weight easily communicates meaning as well as creating rhythm on the page. By creating emphasis you are causing text of an image to seem more important than others. Creating a balanced series of different elements of emphasis is critical to creating a good overall composition: too many different elments of emphasis is chaotic, too few is boring. When the eye is not directed where to look, it tends to just look away.
Look at the Quotation below:
In reviewing the quotation, the eye is immediately drawn to "are" and "feel". Through contrast with weight, you are lead to "don't matter" and "don't mind" and finally the remainder of the statement. The viewer almost "hears" the emphasis allowing the full meaning of the statement to communicate, control and lead the eye.
Examples:
Contrast with Form
Contrast with Structure
Contrast with Texture
Contrast with Color
Contrast with Direction
Contrast with
Weight
Contrast with Size
CONTRAST of Type
