A digestif is an alcoholic beverage served after a meal, in theory to aid digestion. Digestifs are usually taken straight.
Common kinds of digestif include:
Brandy (Cognac, Armagnac)
Eaux de vie (fruit brandies, Schnapps, Calvados)
Pomace brandy (grappa)
Fortified wines (sherry (usually cream sherry), vermouth, port, and madeira)
Liqueurs bitter or sweet (drambuie, amari, herbal liqueur, chartreuse, Grand Marnier, Irish Mist, Kahlua, limoncello)
Distilled liquors (ouzo, tequila, whisky or akvavit)
It is not uncommon for a digestif to be taken before a main course. One example is the trou normand, a glass of Calvados taken before the main course of a meal.