Although the Internet could be viewed as one giant encyclopedia, there is one very important difference: the bulk of the Internet is written by sources with dubious credentials. When you need background information for a school paper or a research project, you not only need it quickly, you need to trust your sources. Here are my recommendations for trustworthy (and free) online encyclopedias.
Although not strictly a general purpose encyclopedia, the Encyclopedia Smithsonian "features answers to frequently asked questions about the Smithsonian and links to Smithsonian resources on subjects from Art to Zoology." Since there is no search function, the only way to navigate is through the rather eclectic A to Z topic listing. Using your browser Find function to search for specific words (Control-F in Internet Explorer, Firefox and Netscape) might be useful on this long index page. Although the interface is chunky, the content is first rate, so don't let it stop you from exploring what the Smithsonian has to offer
High Beam's Encyclopedia.com is composed of 57,000 articles from the sixth edition of Columbia Encyclopedia. Each entry is short but includes hyperlinked references to other encyclopedia articles, as well as links to periodicals and images in the fee-based HighBeam Research Engine. The Web button is a meta-search function that allows you to choose five (of twenty-six) engines to search simultaneously.
It's an almanac. It's a dictionary. It's an encyclopedia. It's Information Please: one-stop shopping for all your information needs. This site integrates the various Information Please Almanacs (sports, entertainment and general knowledge) with Random House Webster's College Dictionary and the Columbia Encyclopedia. It can be navigated by the integrated search function, or you can browse the almanacs by navigating topics. Be sure to test out the fun and useful HotWords. Highlight any word on any Infoplease page, and then click the Hotwords button for a definition and links to related encyclopedia articles.
In contrast to the rest of the today's picks, Wikipedia is not reviewed by an editorial board of experts, but rather by thousands of volunteers. Much has been said about the accuracy of Wikipedia. I chose to include it because for many informal needs, Wikipedia is a useful and vast resource, with +1,335,012 articles in English as of this writing.