almanac, originally, a calendar with notations of astronomical and other data. Almanacs have been known in simple form almost since the invention of writing, for they served to record religious feasts, seasonal changes, and the like. The Roman fasti, originally a list of dies fasti (days when legal business might be transacted) and dies nefasti (days when legal business should not be transacted), were later elaborated into various lists, some of them resembling modern almanacs.
The almanac did not become a really prominent type of reading matter until the introduction of printing in Western Europe in the 15th cent. Regiomontanus produced one of the famous early almanacs (his Ephemerides), incorporating his astronomical knowledge. Most early almanacs were devoted primarily to astrology and predictions of the future. Prediction of the weather has persisted in many modern almanacs, but the crude and sensational magic began to disappear early, to be replaced by more or less scientific information. Late in the 18th cent. truly scientific almanacs appeared—notably the British Nautical Almanac (founded 1767; see ephemeris), which was the inspiration for the American Ephemeris and Nautical Almanac (founded 1855).
The popular almanac, however, developed in the 17th and 18th cent. into a full-blown form of folk literature, with notations of anniversaries and interesting facts, home medical advice, statistics of all sorts, jokes, and even fiction and poetry. The first production (except for a broadside) of printing in British North America was an almanac for the year 1639. One of the best colonial almanacs was the Astronomical Diary and Almanack begun by Nathaniel Ames in 1725, and this was the forerunner of the most famous of them all, Benjamin Franklin's Poor Richard's Almanack (pub. by him 1732–57), which in its title recalled one of the most popular and long-lasting of English almanacs, that of "Poor Robin" (founded c.1662). The most enduring of all American almanacs was first published in 1792 by Robert Bailey Thomas; it came later to be called The Old Farmer's Almanac[k].
The best types of present-day almanacs are handy and dependable compendiums of large amounts of statistical information. Noteworthy American almanacs include The World Almanac and Book of Facts (first pub. as a booklet in 1868, discontinued 1876, revived 1886), and the Information Please Almanac (first pub. 1947, now the Time Almanac). There are also useful almanacs devoted to particular topics, such as sports, health care, Native Americans, and specific countries, or designed for specific audiences, such as children.