In a modern world that demands instant gratification, Port refuses to oblige. After nearly four centuries, it remains a classic fortified red wine whose best examples take years — often decades — to mature.

Born by chance, Port came into being in the early 1700s when England, importing red wine in barrels from Portugal, saw much of it spoil during the long sea voyage. The problem was solved when brandy was added to the casks before shipping. Brandy’s high alcohol content stopped the spoilage; it also stopped the fermentation in the wine, leaving the appealing sweetness of unfermented sugar.

Today, Port is still made the same way. When the crushed grapes are half fermented, grape brandy is added, raising the wine’s alcohol content to about 20 percent and leaving the natural sweetness of unfermented grape sugar.

The finest, rarest and most exalted of Ports is Vintage Port, produced only in exceptional years, from the grapes solely of that year and carrying its vintage on the label. Such a harvest occurs about three or four times a decade, which is why Vintage Port accounts for only 2 percent of Port production. It is declared Vintage Port after spending two years in wood casks.Then it’s bottled where it spends 10, 20 or more years transforming into a smooth, polished gem with many facets of depth, flavor and balance. Among Vintage Port currently on the market are 2000, 1997, 1994, 1991, 1985, 1980, 1977, 1970 and 1960. If you buy a young one, let it age until it is 12, 15 or more years older to enjoy it at its best.

Late Bottled Vintage, or LBV, is Port also made from the harvest of a single year of good quality but not necessarily a year of the great quality declared for Vintage Port; it is generally aged about 10 years.

Tawny Port is a blend of wines from several vintages, aged in the cask for at least eight years before bottling. For the finest, try a 10-year-old or 20-year-old Tawny. Supple and elegant, it is the next best thing to Vintage Port.

Whatever Port you drink, these or any of its many other styles, remember: Although many countries make “port,” only Portugal makes Port. It is the real thing.