Vermouth is a fortified wine flavored with various botanicals, herbs, and spices. It comes in two main types: sweet (red) vermouth and dry (white) vermouth. In the context of alcohol and cocktails, vermouth is used as a key ingredient to add complexity and balance to drinks. Sweet vermouth is often used in cocktails like the Manhattan and Negroni, while dry vermouth is a crucial component in the classic Martini. Vermouth's herbal and slightly bitter profile makes it a versatile and essential ingredient in many classic and contemporary cocktails, enhancing the overall flavor and sophistication of the drink.