"The Verdana fonts exhibit characteristics derived from the pixel rather than the pen, the brush or the chisel."1
--Microsoft Typography website

Verdana is a sans-serif font, designed by Matthew Carter and hinted by Tom Rickner, which was initially released by Microsoft in July, 1996. It was designed specifically with readability in mind, especially with regards to on-screen and multimedia display. To this end, some of the major features of Verdana are:
  • Specially designed font weights, making it possible to differentiate between regular and bold text, even at small sizes. This said, while quite readable at smaller sizes, its more unique characteristics are visible at larger sizes.
  • Wide letterspacing to, once again, aid in character differentiation and readability.
  • Distinctive design for typical "problem" letters and numbers, which tend to often be confused in other fonts, such as "1" and "l", "0" and "O", etc.

So since its introduction, how has Verdana fared? After a series of psychological studies performed at Wichita State University between 1998 and 2002, it was concluded that, in a comparison with seven other "common" fonts, "Verdana appears to be the best overall font choice. Besides being the most preferred, it was read fairly quickly and was perceived as being legible."2

Subjectively, I have to agree with these conclusions, based simply on my own mundane recreational and professional experience with computers. About a year ago, I changed my sans-serif and serif fonts to "Verdana" and "Georgia", respectively, after having vaguely heard something about the two being designed with readability in mind. Months later, the difference has been a true eye-opener (no pun intended), resulting in fewer headaches and tired eyes. I'm no fan of Microsoft, but I have to give them kudos, at least for their work in typography.

Works Referenced
1 "Microsoft Typography - Font Information", http://microsoft.com/typography/fonts/font.asp?FID=1&FNAME=Verdana
2 Usability News, "A Comparison of Popular Online Fonts: Which Size and Type is Best?" (April 1, 2002), by Michael Bernard, Bonnie Lida, Shannon Riley,Telia Hackler, & Karen Janzen. http://psychology.wichita.edu/surl/usabilitynews/41/onlinetext.htm