Vermouth is an aromatised wine—a fortified wine that is flavoured with various botanicals such as herbs, spices, fruit, or flowers. Vermouth is usually defined by the use of wormwood, Artemisia absinthium, as the name 'vermouth' derives from the German word for the plant 'wermut'. While its roots can be traced back to ancient times, vermouth as we know it today was first commercially produced in the late 18th century in Turin, Italy. French brands followed in the early 19th century with their own distinct profiles and it is from these two countries that the main styles of vermouth evolved: rosso, Italian for 'red', a sweet style using caramelised sugar for colour; blanc, French for 'white', a sweet style without caramelised sugar; and dry, referring to low sweetness.

Fortified and aromatised wines, while hardier than table or sparkling wine, are still a natural product and will begin to change after opening. Keep open bottles in the fridge and expect drier wines to last about a month before any difference is noticable. Sweeter and/or more oxidised wines can be expected to take longer for changes in character to develop.