ABV: Alcohol by Volume.  This is measured as a percentage (e.g., Arrogant Bastard Ale is 7.2% ABV).

Alpha Acid: The compound in hops that lend the bitter taste to balance the malty sweetness in beer.

Ale: Beer fermented with ale yeast.  Ale yeast ferments at room temperature 60° – 75° F at the top of the fermentation vessel and creates a fruity, flavorful profile.

Boil Gravity (BG): The gravity of the wort collected from the mash tun, measured right after mashing, but before boiling.  Taking this measurement allows the brewer to assess the efficiency of the mashing process.

Conditioning: Secondary fermentation, when the yeast refines the flavor of the beer.  This process continues in the bottle during bottle conditioning.

Dry Hopping: Adding hops to beer in the fermenter (usually the secondary fermenter, or after primary fermentation is complete)

Ethanol: The type of alcohol in beer.  Ethanol is a waste product of yeast consuming malt sugars in wort.  This is the compound that makes you happy when you drink.

Fermentation: That mystical/magical process where yeast converts wort to beer.  The yeast eats the sugar in the wort (at least it eats the fermentable sugars) and produces two desirable waste products – alcohol and carbon dioxide (CO2).  If these two by-products sound familiar to you, go to the head of the class.  Alcohol is an important ingredient in beer (duh!) and what would beer be without carbonation (CO2)?

Final Gravity (FG): See “Terminal Gravity”

GABF: The Great American Beer Festival.  This event is held each year in Denver, Colorado.  It it the apex of American brewing.  Winning a gold medal at GABF is like winning the National Championship.  It doesn’t get any better than this.  If you win gold here, you are at the top of your game, SECOND TO NONE!

Hops: The cone like flowers from the hop vines (Lupus Salictarius, meaning wolf among scrubs; so named by a Roman Captain, Pliny the Elder, in the first century A.D.) that brewers use to bitter and flavor beer.  Hops are available in pellets (most common), plugs, or whole.  There are numerous varieties of hops – some used for bittering, some used for flavor, some used for aroma, and some for all three.

International Bitterness Units (IBUs): Measurement of how much of the alpha acid is isomerized from the hops and dissolved into the beer.

Kraeusen (pronounced kroi-zen): The foamy, nasty looking layer of yeast and crud covering the top of the wort in the fermenter.  It’s typically a creamy color, with brown and/or green patches.  The crud is composed of wort protein, hop resins and dead yeast.  The kraeusen layer is typically a couple of inches thick, and subsides as primary fermentation winds down.  The crud is pretty much insoluble, and sticks to the sides at the top of the fermenter (above the beer), so does not affect the flavor of the beer.

Lager: Beer fermented at cold temperatures using lager yeast.  Lager yeast ferments at the top of the fermentation vessel at approximately 45° – 60° F, and creates a very clean, crisp flavor profile.  Taste a black lager (schwarzbier) next to a porter or stout (ales) and you will taste the difference between a lager and an ale.

Malt: Barley grain that is modified to produce enzymes and starches that are useful to the brewer.  The grain is steeped in water, held for awhile at controlled a temperature and humidity until the seed starts to germinate.  The germination is halted by drying the grain in a kiln.  Some malt is kilned ,toasted or roasted at higher temperatures to create different flavors and colors (specialty malts).  These specialty malts release sugars with differing degrees of fermentability and sweetness, allowing the brewer to make different tasting beers – ambers, browns, stouts, etc.  Other grains are also malted, (e.g., wheat and rye) and their use will create different flavor profiles.

Mash: Grain (typically barley and/or wheat, but there are other grains used as well) mixed with a measured amount of hot water (at a specific temperature) for a specific amount of time.  This process (called saccharification) converts the starches/sugars in the malted grain to soluble, fermentable sugars.

Mash In: The process of combining the grain with the measured amount of water at a predetermined temperature to start the mash.  Hopefully you have made accurate calculations to get the initial mash temperate correct.

Mash Tun: The vessel in which the grain is mashed.

Original Gravity (OG): The term used (expressed as a number value) that describes the sugar concentration in wort.  This value is measured by hydrometer or refractometer after boiling the wort, before fermentation.  In general, the higher the OG, the higher potential alcohol yield.

Pitching: Adding yeast to the fermenter.

Priming: Adding a small, measured amount of sugar (usually corn sugar) to the fermented beer when bottling.  The yeast that is still in the beer will consume the sugar and produce CO2 (a by-product).  Because the beer is contained within an enclosed bottle, the CO2 can not escape and the beer is carbonated.

Racking: Gently transfering beer from one vessel to another.

Terminal Gravity (TG): Also typically called final gravity (FG).  This is a measurement of the sugar concentration in the beer after fermentation.  If the brewer knows the OG and the TG, he can calculate the alcohol content of the beer ([OG – TG] x [constant value of 131] = alcohol content by volume).

Trub (pronounced troob): The crud (sediment) left at the bottom of the fermenter.

Wort (pronounced wert): The solution of sugar-water produced by mashing.  The wort is boiled for a specific amount of time (usually 60 or 90 minutes) with hops.  The boiling serves two purposes – pasteurizes the wort, and changes the compounds in the hops to give beer its bitterness.  The boiled solution (with the hop bitterness, flavor and aromas) is still called wort until it is fermented, when it becomes beer.