The term vintner is applied to wine merchants as well as winemakers. Wine merchants buy and sell wine, while winemakers, sometimes also known as oenologists, produce wine or supervise the production of wine. This includes cooperating with viticulturists, monitoring the progress of grapes to ensure their quality and to determine the correct time for harvest, crushing and pressing grapes, monitoring the settling of juice and the fermentation of grape material, filtering the wine to remove remaining solids, testing the quality of wine, placing filtered wine in casks or tanks for storage and maturation, and preparing plans for bottling wine once it has matured and make sure that quality is maintained when the wine is bottled.
Today, these duties require an increasing amount of scientific knowledge, since laboratory tests are gradually supplementing or replacing traditional methods. Nonetheless, a vintner still requires an excellent sense of taste and smell.