Beer is an alcoholic beverage made from four primary ingredients: water, grains, hops, and yeast. The grains used in beer production include barley, wheat, rice, corn, oats, and rye, and they must undergo a malting process before they can be used to make beer. During the malting process, the grains are soaked in water until they start to grow, and then they are dried in a kiln. This process metabolizes the natural grain sugars, called maltose, which is what the yeast feeds on during fermentation. Hops are used in most modern beer to add bitterness and other flavors, as well as to act as a natural preservative and stabilizing agent. Yeast is a living organism that feeds on sugar and converts it to alcohol and carbon dioxide. Finally, water is a crucial ingredient in beer production, as it can have varying levels of mineral content that can significantly affect the taste of the beer.

In summary, beer is made from the following four primary ingredients:

• Water
• Grains (barley, wheat, rice, corn, oats, rye)
• Hops
• Yeast

These ingredients are combined and fermented to become alcoholic, and even small changes in the brewing process can change the color, taste, and aroma of the beer.