Reading about wine is a necessary adjunct to drinking it, if for no other reason than that it focuses the mind on the glass in hand. Remembering the characteristics of individual wines is essential to increased appreciation of them, and looking them up in a claret-stained book is a good mnemonic device. Like wine itself, wine books are big business, with new ones coming on the market every season.

Even if you have little interest in reading about specific vinicultural areas, you will nevertheless need a good reference work. The best is still Hugh Johnson's Modern Encyclopedia of Wine (Simon and Schuster, $30), a 500-page compendium that manages to combine a lot of information with good journalism -- a rarity among wine writers.

My choice for second place is the old standby of the late Frank Schoonmaker, Encyclopedia of Wine (Hastings House, $15), published 20 years ago, somewhat updated, dry as cellar dust and still the fastest look-up for the beginner. A new reference book, with more emphasis on individual wineries and chateaux, is Terry Robard's New Book of Wine (Putnam, $20), ambitiously subtitled "The Ultimate Guide to Wines Throughout the World." It has sections on wine production and wine drinking and easily accessible commentary by a writer intimately involved in the trade.

One of the most unusual books to appear during the last year is Steven Spurrier's Concise Guide to French Country Wines (Perigee, $6), which uses good paper, maps and color reproductions of some labels. A French country wine means to Spurrier "a wine which is drunk by locals and tourists in the place where it is made, which has certain defined regional characteristics and is not too sophisticated or expensive." In short, the sort of wine most of us drink. Many of them find their way here, but even if they didn't you would learn a lot about French wine in general from this elegant paperback.

Several books about American wines have appeared, some heavier on photographs than information. One problem publishers have with macro-enology in this country is that most people are not interested in, say, Arkansas muscat. In some cases they should be, according to Leon Adams, whose massive The Wines of America (McGraw-Hill, $23) has been reissued. In the half-dozen years since the last revision appeared, 450 new wineries have added to the already staggering number of commercial wine producers in the United States. Adams has a no-nonsense approach to them and to wine, which he rates simply according to "palatability," without all the attendant adjectives. What his book lacks in inspirational writing it more than makes up for with facts.

Books about California wines, like the wines themselves, proliferate. An outstanding one combining real people with the admittedly daunting amount of California product has yet to be written. The new edition of The Connoisseur's Handbook of California Wines (Knopf, $7) is handy. It offers thumbnail sketches of vineyards and wines, with a simple rating system, although readers should not take the writers' palates as flawless (or any wine writer's, for that matter). Another California update, the third edition of The Fine Wines of California (Doubleday, $10), by Robert Blumberg and Hurst Hannum, is an extensive and valuable study of varietals, geography, history and individual wineries, and includes some maps, but it is a bit of an organizational muddle. Both books will help you sort out our fabulous national phenomenon, the California vineyard.