One of the most intriguing and least understood drinks is sherry, a fortified wine with a great tradition that seems at odds with current tastes. Sherries can be large, alcoholic affronts to palates honed on wine coolers and innocuous whites, but they can also be styled to suit almost any taste. Indeed, versatility is one of sherry's attractions.

A pale fino makes a good aperitif; a cream sherry provides a nectarlike finish to a substantial meal. In between, a good amontillado is a fine match for walnuts shelled in front of a fire on a rainy afternoon.

Sherry is named for the Andalusian town of Jerez in south- west Spain. The region's clay soils contain a high percentage of chalk, an element that contributes to distinctive wines in other parts of the world like Chablis and Champagne. The strong white wine produced from grapes grown near Jerez, in the constant heat, is rather ordinary by most standards, but the fermenting of the grapes is just the beginning of the sherry-making process.

The naturally high levels of alcohol in the wine are augmented by the addition of spirits, bringing the alcoholic content up to between 16 and 18 percent, several degrees above that of unfortified wine. The alcohol and sugar give sherry a long life and an ability to travel, which made sherry one of the first wines for export. In medieval times sherry was shipped in great quantities to England, where it was popular for its durability, its sweet, complicated taste and its punch.

It was called "sack" in reference to the French sec, meaning dry. A "cup of sack" was the standard order in a 17th-century tavern, although the beverage was neither French nor dry. But sweetness and alcohol are nothing without the taste of oak and oxidation -- air contact that spoils most wines but with sherry contributes to the unique flavor.

This is achieved by blending wines aged for different lengths of time in a system known as the solera. The wine is shifted among a series of 500-liter oak "butts" to achieve the desired style. When the oldest sherry is taken from the final butt in the series, that butt is topped up with wine from the preceding barrel; that barrel is then topped up with slightly younger wine, and so on up the line. The newer wine in each butt soon takes on the characteristics of the older. The aging is gradual, and the final product has remarkable continuity.

Fino is the lightest version of sherry. During fermentation it is covered with a yeasty scum known as flor, which cuts down on the oxidation and keeps the wine relatively clear. Fino is ready to drink sooner and has a more delicate aroma.

Amontillado, probably the most popular style of sherry, is named after the town of Montilla. Simply stated, amontillado is a medium-style sherry, a fino with some age and nutty character picked up by the extra wood contact.

Oloroso has more body and a pungent, woody intensity that gives added character to lighter wines when blended with them.

Cream sherry is a blend of sweet oloroso. It can be light in appearance or colored by the addition of darker wine called vino de color.

A rare treat is palo cortado, with the elegance of a fino and the depth of a good oloroso. Similarly, palo cortado can be dry or sweet, but it always seems to elicit a sigh of appreciation from those tasting it for the first time. It's difficult to find, but well worth the effort.