"Before graphic user interfaces, text was the primary means of both input and output defining human-computer interactions. Even today, much of the information user interfaces present is textual. Therefore, we should not underestimate how the right text treatment can measurably improve user productivity and increase user satisfaction. As new technologies become available—for example, larger monitors with higher resolutions—a good foundation of knowledge about effective text treatment can help designers create usable user interfaces for them more quickly.
Content developers have hundreds of serif and sans serif fonts at their disposal. Serifs are small lines at the ends of the main strokes of characters. Serif fonts improve readability in continuous text, because the serifs help readers to structure and discriminate characters . Times New Roman, for example, is a serif font, as Figure 1 shows. Typically, newspapers, magazines, and books use serif fonts.
Sans serif fonts like Arial do not feature these little strokes, as you can see Figure 1. On computer screens, sans serif fonts are preferable, because relatively low screen resolutions—typically around 100 pixels per inch rather than the 800 dots per inch of print—make serif fonts look fuzzier, especially in small sizes.
The new generation of e-books such as the Kindle from Amazon have much higher pixel densities than current PC monitors—around 170 ppi. This makes it possible to use serif fonts—as in a real paper book—improving the overall user experience. So the choice between serif and sans serif fonts depends on the capabilities of the target output technology." (Continued via UXmatters, Tobias Komischke) [Usability Resources]