What four primary ingredients are used to make beer?

Though used in varying proportions depending on the style of beer being made, beer is made from grain, hops, yeast, and water.

The grains (barley, wheat, rice, corn, oats, rye, etc.) are much the same as those that are used to make many breakfast cereals. The barley and wheat must undergo a malting process before they can be used to make beer (the others do not). The malting process simulates grain germination, which metabolizes the natural grain sugars (called maltose), which is what the yeast feeds on during fermentation.

The hops provide beer with piquant aroma, a variety of flavors, and a delicate-to-intense bitterness that balances the sweetness of the malt.

During fermentation, yeast consumes the sugars derived from the malted grain and excretes ethyl alcohol and carbon dioxide in return.

Considering that beer consists of up to 95% water, the quality of the water is of great importance. Depending on its source, water can have varying levels of mineral content, and this minerality can have a significant effect on the taste of the beer.