The reason the cocktail made it big in the happy '20ies, was the prohibition, when producing and imbibing of alcohol was made illegal. As good as all spirits available was of a rather dubious quality and tasted accordingly. Thus, the bartenders, accommodating as always, started to mix the spirits with various fruit juices and other flavorings to make it more palatable. Later, the cocktail lost its popularity most places, the United States being the main exception. The last few years, however, the cocktail has reclaimed lost ground everywhere, especially in southern Europe and other places that are full of tourists.
Cocktails usually consist of three different 'classes' of ingredients.
The first, the base, is most often some sort of spirit, like vodka, whiskey, or tequila. Occasionally, such as in many punches, some sort of wine is being used as a base. The second, the main flavoring, is added to bring out the aroma of the base and to modify its taste. The main flavoring is often such as Vermouth, various fruit juices, wine, or even eggs or cream. The third, the special flavoring, is added to enhance the taste of the base, and often also adds the color to the cocktail.