Consider: Volunteers write every article - and anyone with a web browser and an Internet connection can update them at any time. What's more, it is possible to search the entire Wikipedia database and use the material for any purpose. Already, Wikipedia appears in 123 languages, including Hebrew, Croatian, Tagalog, Vietnamese, and Esperanto. "We're able to harness more brainpower than other encyclopedias," says Wales. "Our approach and format give a distinct advantage over other encyclopedias."

However, not everyone considers Wikipedia a beacon of progress. In recent months, a spate of inaccurate entries have garnered headlines and raised questions about the encyclopedia's integrity. Articles about high-profile and controversial figures, such as President Bush and Sen. John Kerry, have become the target of vandals. Finally, some argue that a highly successful and free Wikipedia could undermine established providers of reference materials and threaten their viability. If these encyclopedias falter, the theory goes, society could wind up with a set of less-than-accurate ­reference books.

Consider it an irony that the word encyclopedia derives from a classical Greek phrase meaning "a general or well-rounded education." Although such reference sets have existed since the sixteenth century - and were once viewed as essential learning and study guides - they have slowly evolved into a source for quick information. Moreover, the advent of CDs, DVDs, broadband, and the web has moved the emphasis away from print and toward pixels. Let's face it: The luster of owning a $1,500 set of encyclopedias isn't what it once was - especially when you consider that they're obsolete as quickly as they are printed.