The most basic response to this question is that wine is made by fermentation. Grapes are crushed and their juice is enabled to ferment, usually with the addition of yeast. The yeast consumes the sugars in the grape juice and convert them into alcohol. There are, naturally, numerous more details involved in making red wine.
White red wine is made by crushing the grapes and separating the juice from the skins prior to fermentation. Red wine is made by squashing the grapes and permitting the skins to stay in contact with the juice during fermentation.
There are several kinds of white wine, and the information of how they are made differ depending upon the design of wine being produced. In general, however, red wine is made by fermentation of grape juice. The kind of grape, the environment in which it was grown, and the soil composition all play a function in the taste of the wine. The fermenting and squashing process can also be controlled to produce various flavors and styles of red wine. site link