The most basic division in typography is between serif and sans-serif typestyles. A serif typeface has serifs--small lines, flourishes or embellishments on the top and bottom of its characters. Think of Times New Roman--that's a serif font. Sans-serif letters like Helvetica lack these extra strokes on the character. There are several more specific categories within the serif and sans-serif groups. For example, Modern typefaces have a large contrast between thin and thick strokes, and Geometric typefaces have even strokes and large apertures. The aperture is the space within a circle, such as a lowercase "a" or "o."
Serif fonts are used mainly in printed documents because the extra stroke allows the word to be seen and read as a unit, rather than as a group of individual letters. This makes for faster and easier reading. However, the resolution on a computer screen is much lower than on a printed page, so serifs can blur and become illegible when viewed on a monitor. According to the Complete Reference Web Design, sans-serif fonts maintain their shape better on screen. For the best legibility, choose a sans-serif typeface for online use and a serif type for printed text.
For titles, headlines, and accent text, experiment with decorative typefaces. Any typeface with a "strong personality," as Webmonkey calls it, is considered a decorative font. Thousands of non-traditional typefaces, each with its own flavor, are available. Some of the common decorative font groups are "grunge" fonts with a "dirty" look, fonts with a "Wild West outlaw poster" feel, and fonts designed to look like handwriting. Decorative typefaces make effective accents, but they're generally too difficult to read in large blocks of text.
If you create your document in a page layout program such as InDesign, Scribus or Microsoft Publisher, you'll have more control over letter spacing in your finished document. Adjust "kerning" to reduce or enlarge the horizontal space between individual letters. To add or subtract space between each line of text, adjust the "leading." Kerning and leading are the two most basic type adjustment tools available in any page layout program. Experiment with letter spacing to change the style of the page and increase readability.