Dry Vermouth
Vermouth is a fortified wine aperitif, flavoured with herbs, spices, barks, and flowers. There are various brands of vermouth produced in both Italy and France, and the flavors can be added through infusion, maceration, or distillation. The name "Vermouth" itself derives from the German "Wermut" (Wormwood, and ingredient in Vermouth).

The original version of Vermouth that was used in cocktails was from Italy, and is what we often refer to today as Sweet Vermouth. Thus any cocktail recipes you might find prior to 1900 which simply listed "Vermouth" as an ingredient, were intended to use Sweet Vermouth. Eventually the French (dry/white, as opposed to sweet/red) version of Vermouth started making its way into cocktails, and so recipes would differentiate between the two by specifying "Italian Vermouth" or "French Vermouth". Since most vermouth manufacturers today make both types of vermouth, it is more approriate to refer to them as Sweet Vermouth (Italian/Red) and Dry Vermouth (French/White).