More brewing basics and required (?) knowledge.
The yeast is perhaps the most important ingredient in beer. Yeast turns fermentable sugars in the wort into alcohol (one of our favorite things), carbon dioxide, and various scents and flavors in the form of esters, alcohols, phenolic compounds, and other volatiles. If you were to take on batch of wort, split it into two containers, and add a different yeast to each one, you could wind up with drastically different beers. Yeast practically defines the style of the resulting beer (some styles much more than others), while the other ingredients will handle touches that make it different from other beers in the style. My yeast comes from Wyeast, who sell their yeast in a wonderful package called a smack pack. The package itself contains dormant yeast, and a smaller, sealed nutrient pack. You smack the heck out of the thing with your hand to bust the inner package, and then the yeast feasts on the freed nutrients. After a couple of hours (I leave mine overnight), the pack swells an amount somewhere between ‘noticeable’ and ‘I think it’s going to bust.’ Pitching healthy yeast in the right amount for your wort is absolutely clutch. For an average beer (O.G. <1.060), a single Wyeast smack pack is adequate. For higher gravity (higher alcohol) beers, more yeast is necessary. White Labs is another well-known and respected producer of brewer’s yeast. All my experience has been with Wyeast, and I have been nothing but satisfied with them, so I probably won’t change. White Labs doesn’t sell the smack packs; rather, they ship their yeast in vials. Dry yeast is also available, but not nearly in the wide selection the liquid yeast it.
The fermentables form the backbone of the beer. The most common fermentable is malted barley. Get some malted barley, crush it, and steep it in water to get a sort of barley tea. This leaves behind sugars and enzymes, and controlling the temperature of the steeping will affect what sorts of compounds you will wind up with in the beer. When using specialty grains alongside malt extract, it is commonly said not to steep it for longer than twenty minutes and not to heat it over 170 degrees F. Doing so will release some compounds that will negatively affect the beer’s flavor. You also shouldn’t press your grains while they are steeping (e.g. to ‘squeeze’ out water, or flavor, or whatever you’re trying to do). This will release undesirable astringent tannins into the beer, and they don’t exactly enhance the final product. To simplify the process, small scale homebrewers typically use premade malt extract. You can get extracts from any homebrew shop in a variety of types. To make extract, a base wort is made with appropriate grains and then, instead of moving on to the next brewing step, they just boil it down. You can get liquid extracts (LME) or dry powder extracts (DME), the two of which are equivalent excepting some minor water content present in the liquid extract (6lbs LME = 5lbs DME). Some places also sell pre-hopped extracts, but these are typically recommended against.
The hops were not originally in beer thousands of years ago. They used all manner of plants and flowers, but hops only came into use within the last thousand years in Europe. Hops are ubiquitous in beer now for a few reasons. First and foremost, they have an antibacterial effect and keep unwanted microorganisms out of beer while in normal levels not really affecting brewer’s yeast. When shipping beer on long voyages, sailors found hopped beer to keep longer than unhopped beer. Second, their bitterness balances out the sweetness of the malts. An unbalanced, overly malty beer is difficult to drink. Likewise, though, many people find highly hopped beers equally difficult to drink. The most common styles that are high in hops are India Pale Ales (IPAs). The light malts used in IPAs simply can’t overpower big quantities of hops and so the bitter, grassy hop flavor dominates. Big beers, like stouts, porters, etc. have a high amount of hops as well, sometimes surprisingly high, but higher quantity of malt and darker malts balance the bittering effect. The hops are an integral part of balancing the flavor of big beers. For homebrewing purposes, hops come in several forms including whole leaf and pellet. You can even grow your own hops, if you’re that sort of person (though I don’t believe they’ll grow well in the southern US).
Water makes up 85-95% of beer. If you don’t like drinking your tap water, you won’t like the beer you make with it. Go pick up some spring water from the grocery, or invest in a water filter if need be. A $20 filter pitcher or sink attachment will give you 40+ gallons of purified water per $5 filter, while buying jugs of water will cost $0.50-0.75 per gallon. If you invested in some equipment, you’re probably going to be brewing more than one batch of beer. Invest in the filter if your drinking water doesn’t taste that great. There is a fair amount of literature out there on the desired elemental composition of water for brewing purposes, but it is well beyond the scope of me giving a damn right now. Styles like pilsner are actually dependent on water chemistry and came about because of the unique composition of local water (water from Plzen, Czech for example, made a unique beer at the time).