Wine is fermented grape juice. That's the standard answer. Actually, wine can be made from all sorts of common and not so common foods. Things like fruits, herbs and flowers. Most wine, though, is made from grapes. And no matter what the wine is made from, there must befermentation, that is, thatsugar be transformed into alcohol. If the amount of alcohol is relatively low, the result is wine. If it is high, the result is a"distilled liquor," something like gin or vodka. Or perhaps the ever popular 151 rum ("flammable, use with caution").
By the way, as fermentation cannot increase alcohol content past about 16%, for at that level the yeast dies and ends fermentation. Higher alcohol levels are archived through"distillation" (that is a lower alcohol beverage is heated. Alcohol, evaporating first, is collected and the vapor re-condensed).
There are red wines, pink wines (also known as "rose" or sometimes "blush") and white wines. Since the inside of a grape is more or less "white," red grapes can make white wine. The color comes from letting the juice mix with the skins during the early wine-making process. A good example of this is White Zinfandel. The Zinfandel grape is very red on the outside. So, red grapes can make white wine, but white grapes can't make red wine.
Wines might be "fortified," "sparkling," or "table." In fortified wines, brandy is added to make the alcohol content higher (around 16 to 23 percent). Sparkling wines are the ones with bubbles, like Champagne. Table wine (which can also be called "still wine") are the most "natural." Both table and sparkling wines tend to have alcohol contents between 7 and 15 percent.