GDI organizes fonts by family; each family consists of typefaces and fonts that share a common design. The families are divided by stroke width and serif characteristics. The term stroke, which means a horizontal or vertical line, comes from handwritten characters composed of one or more pen strokes. The horizontal stroke is called a cross-stroke. The main vertical line is called a stem. Figure 2.10 shows a lowercase f composed of a cross-stroke and a stem with a loop at the top:
Serifs are short cross-lines drawn at the ends of the main strokes of a letter. If a typeface does not have serifs, it is generally called a sans-serif (without serif) typeface. Figure 2.11 shows serifs:
GDI uses five distinct family names to categorize typefaces and fonts. A sixth name is used for generic cases. Note that GDI's family names do not correspond to traditional typographic categories. Table 2.4 lists the font-family names and briefly describes each family:
Table 2.4 Font Families
| Name | Description | |
| Dontcare | Generic family name. Used when information about a font does not exist or does not matter. | |
| Decorative | Novelty fonts. Old English, for example. | |
| Modern | Constant stroke width (fixed-pitch), with or without serifs. Fixed-pitch fonts are usually modern. Pica, Elite, and Courier, for example. | |
| Roman | Variable stroke width (proportionally spaced), with serifs. Times̉ Roman, Palatinỏ, and Century Schoolbook, for example. | |
| Script | Designed to look like handwriting. Script and Cursive, for example. | |
| Swiss | Variable stroke width (proportionally spaced), without serifs. Helvetica and Swiss, for example. | |
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