Serif fonts include extra feet at the ends of the strokes and vary in line weight within the shape of each letter. In general for print applications, serif typefaces are most legible because the serif adds differentiation between letter forms, yet on lower resolution and small monitors, this may not always be true. Examples of serif fonts include Times New Roman or Courier and Century Schoolbook. Choose fonts based on their legibility, and avoid using several types of fonts mixed together or very narrow or decorative fonts. Type weight refers to the thickness of the letters .
Many typefaces are available in light or narrow or bold or extra bold.
While boldfaced text appears larger, readability can decrease if all of your text is bold. Use bold to emphasize a title or a key word. The space between the letter and lines. Additional space between paragraphs and sections within a document can provide the eye breathing room. Avoid reduced kerning, or condensed spacing.