The most popular reference sites on the Web according to Alexa.com's Top 100 Web sites in the US as of Jan 17, 2011 are Wikipedia at No. 6, the second at No. 23 is the Internet Movie Database and the third is About.com at No. 30; then the author realized that he has seen it frequently in search results. What About.com does quite well is to serve as an online version of the highly popular Dummies and Idiot's Guide book series. In other words, it explains things concisely, simply, and clearly. If About.com is an online version of the For Dummies and The Complete Idiot's Guide series, the originals are also on the Web, each with large sites that contain copious amounts of content from the books. The principal differences between the two sites are that the For Dummies site is much larger than The Complete Idiot's Guide, and it has much more content per subject.