Homebrew beer is produced by adding yeast to a wort made from mashed malted barley or diluted malt extract. Many brewers rely on kits and malt extracts whilst some progress to making their wort from crushed malted barley. During all stages attention to sanitation is essential. All items that come in contact with the wort or brew, must be soaked in a sanitizing solution and thoroughly rinsed, or immersed in boiling water. When using malt extract, additional steps can be taken to add different flavors. Specialty grains are malted grains that do not require mashing. They are commonly steeped to add flavor, body and color at the beginning of brews. Sometimes hops are added at later stages for aroma and flavor, or dry hopped, (added just after secondary fermentation). There are several instruction books available. Some are more detailed than others, but homebrewing can be as simple or as complicated as you want it to be.

Kits
Kits contain liquid malt extract that, when reconstituted with water, produces wort. They are the easiest method available since the basic varieties typically don't require boiling or other preparations. Generally, the quality of beer from these kits is not on par with beer made from all-grain or malt extracts, but can be a good start for someone overwhelmed by the process.

Extract brewing
The process of brewing beer starting with cans of pre made malt extract. Having mastered kits, homebrewers can experiment with their own recipes by boiling water, malt extract and hops together in a large kettle or boiler; then cool the resulting wort before fermenting. Extract brewing still saves considerable time against any mashed brewing processes. An extract brew can be completed from start to finish in around two and a half hours, as such it remains a popular homebrewing method. Many homebrewers achieve excellent results with extract recipes. Boiling a quality extract with hops can produce good facsimiles of many classic brews. However, some brewing adjuncts, (other grains added to beer), need to be converted by enzymatic reactions involved in mashing to be useful in brewing; therefore some homebrewers use a method called partial mashing

Partial mash
The next step up from extract brewing is to use a diastatically active malt extract to convert starches from other beer adjuncts. This process usually involves steeping a bag of specialty grains in the reconstituted malt extract to convert the malt starches into sugars. The most basic of partial mash setups uses a pound or two or specialty grain in a muslin bag which is placed directly into the simmering water. This method does not result in a very high percentage yield of coinverted starches though. Partial mashing can get as complex as multiple pounds of grains in a full mash like process, but always uses malt extract as the primary source of converted malt sugars. Partial mash brewing adds a level of flavor depth unattainable from simple extract brewing alone.

Full mash
The most complicated method is to manufacture extract from crushed malted barley by mashing the grain in hot water. This requires an insulated vessel known as a mash tun. This method is typically known as full mash brewing. Quick cooling and isolation from the ambient atmosphere is needed to prevent early bacterial contamination or oxidation of the wort. Often, cooling is hastened by the use of thermal heat exchangers, informally, wort chillers, which often consist of copper tubing immersed in the wort, through which cold water flows. For larger volumes of wort, a counter-flow wort chiller can be used, in which the hot wort flows through copper tubing which is jacketed by a second tube (often garden hose) through which cold water is run in the opposite direction from the wort's flow. A more primitive and ineffective method is to immerse the pot in a sink full of ice water.

Fermentation
The cooled wort is poured into the primary fermenter in an aggressive manner, so as to aerate the wort. Sufficient oxygen is vital for the yeast's growth stage. Advanced homebrewers may further oxygenate the wort by bubbling filtered air or even pure oxygen through the cooled wort. The yeast is then pitched (sprinkled or poured) into the wort. If a dried yeast is used, some brewers rehydrate it first to reduce 'lag time', or the time taken before the yeast starts working. Although more expensive than dry yeasts, a number of liquid yeasts are also available, offering a range of flavor characteristics that allow the brewer to more closely approximate various beer styles.

Primary fermentation takes place in a glass carboy or plastic food-grade bucket, nearly always sealed, but traditionally can be left open. When sealed, the fermenter is stoppered with the carbon dioxide gas produced venting through a fermentation lock. During this time, temperatures should be kept at optimum temperature for the fermentation process. For ale this temperature is usually 65-75°F / 18-24°C, and for lager it is usually much colder, around 50°F / 10°C. A vigorous fermentation then takes place, usually starting within 12 hours and continuing over the next few days. During this stage the fermentable sugars (maltose, glucose, and sucrose) in the wort are consumed by the yeast, while ethanol and CO2 are produced as byproducts by the yeast. A layer of sediment, the trub, appears at the bottom of the fermenter, composed of heavy fats, proteins and inactive yeast. A sure sign that primary fermentation has finished is that the head of foam (krausen), built by bubbling of CO2, falls.

Conditioning
Often, the beer is then racked (siphoned) into another container, usually a carboy, for aging or secondary fermentation. Fermentation is actually complete, so the term secondary fermentation actually refers to conditioning. Racking is done to separate the batch from the afore-mentioned trub so that it is not used as food, as this can give the beer an off-flavor. Racking also helps separate the beer from sediment, making it less likely to find its way into the finished product. During secondary fermentation some chemical byproducts from the primary fermentation are digested, which considerably improves the taste. Secondary fermentation can take from 2 to 4 weeks, sometimes longer, depending on the type of beer. Additionally, lagers are aged at this point for at near freezing temperatures for 1-6 months depending on style. This cold aging serves to reduce sulfur compounds produced by the bottom-fermenting yeast and to produce a cleaner tasting final product with fewer esters. Some homebrewers will keep the batch in the primary fermenter, called single stage fermentation, for the entire process. The potential drawbacks include added sediment in the finished product and a greater risk of off flavors. The tradeoff is this eliminates the need for a second container, reduces labor, and reduces the likelihood of contaminating the batch with bacteria, or oxidizing it, during transfer to the second container. This is a good beginner strategy, especially for those not skilled with racking.

Carbonation
Once secondary fermentation is finished, the beer is ready for carbonation. There are two methods of carbonation. The first method does not require much capital expenditure per batch but is more time consuming. About 3/4 cup of corn sugar (dextrose) or other fermentable sugar is added to the beer, which is then transferred to bottles and then capped, or placed in a keg. The fermentation of the priming sugar in the closed container by left-over yeast suspended in the beer creates carbon dioxide which then dissolves into the beer. This takes 1-2 weeks. The second method involves pressurizing carbon dioxide into the beer into a special type of keg - either a Cornelius keg, the kind used in restaurants for soda storage, or a pressure barrel. Canisters of carbon dioxide, or soda chargers, can be released into the pressure barrel directly. The carbonation process then occurs almost instantaneously.

Using the first carbonation method, sediment will remain at the base of the bottles after completion. At this point it is referred to as the dregs, and an experienced homebrewer learns how to decant the beer, with minimal contribution to the taste of the beer in the mug. Some wheat beers, however, demand the sediment be rotated through the beer before it is served.

When using natural carbonation, the fermentation process restarts, although in a much smaller scale. The yeast must ferment the sugar, then clean up the byproducts of fermentation as in the secondary phase. Because the yeast population is much smaller, the process can take up to and beyond two weeks beyond full carbonation. Once the bottle/keg conditioning phase ends, the beer begins aging. Aging typically rounds out any rough edges in the beer and can remedy many imperfections. Some beers such as wheat beers are considered best with little to no aging, while bigger, higher alcohol beers can benefit from age for years.