The foundation of Britannica Online is the Encyclopaedia Britannica, the largest, most authoritative encyclopedia in the world. Besides topical articles, it includes maps, photos, illustrations, videos, multimedia clips, and yearbooks from 1993 onward.
It also includes easy access to the Merriam-Webster Dictionary & Thesaurus.
Some very cool features of Britannica Online are the interactive timelines on a range of topics, from architecture to women's history, as well as side-by-side country comparisons.
Additional research tools are the World Data Analyst, a World Atlas, Notable Quotations, and Gateway to the Classics.