Figure 13.6: The serif typeface Century below versus the sans serif typeface Univers,above.Understanding the differences within the typeface as well as what the differences between a serif and a sans serif is important.Try setting a paragraph of each with exactly the same line length,size and spacing to compare the differences.                     

Suzanne Watzman (2003). Visual Design Principles for Usable Interfaces In: J. A. Jacko and A. Sears (Eds) The Human-Computer Interaction Handbook. © 2003 by Lawrence Erlbaum Associates.  All Rights Reserved.