Definitions

Let’s get the ball rolling with some definitions so we can all be on the same page about the basics.

Beer: An alcoholic beverage made by brewing and fermentation from cereals, usually malted barley and flavored with hops and other sometimes other ingredients

Ale: A classification of beer styles. A style made with a top fermenting yeast, ales generally are hearty, robust, and fruity. 

Barley:  The grain used to produce the malt used in brewing.

Brewing:  The art of making beer. 

Fermentation: The process of the yeast converting the simple sugars in the wort in a complex sequence of 13 discrete steps to alcohol and carbon dioxide. Fermentation can take up to seven days. 

Germination: The stage in the beer-making process in which the steeped barley grains are drained and allowed to sprout for seven to nine days

Head: The foam at the top of a beer. The head is the protein which is pushed out of suspension by the bubbles. 

Hops:  The flower of a perennial vine, and one of the four ingredients of beer. Hops are the universal spice of beer. Hops, like grapes used in wine, are varietal. Some varieties contribute mainly bitterness, while others are prized for their fine aromas.

Lager: A classification of beer styles made with a bottom fermenting yeast, lagers generally are smooth, elegant, crisp, and clean.

Malt, Malted Barley: One of the four ingredients of beer. Malt is barley which has been moistened, allowed to germinate, and then dried. The variety of barley, the extent to which it is allowed to germinate, and the temperature at which it is dried all influence the character, the color, 
and the flavor of beer. 

Mashing: The process of combining the ground malt with water. Mashing is performed at either a constant temperature, or a series of rising temperatures, depending on the brewing equipment, the raw materials being used, and the type of beer being brewed. The 
mashing process determines the composition of the wort. 

Pasteurization: Beer must either be pasteurized or sterile-filtered to protect it from the continued growth of any stray yeast or other beer loving micro-organisms.  Pilsner: A general name for pale, golden-hued, highly hopped, bottom-fermented beers. The original was first brewed in the Bohemian town of Pilsen in 1842. 

Porter: A very dark, top-fermented beer first brewed in London in 1722 by a man named Harwood as a substitute for a then popular mix of ale, beer, and two penny beer. Called Entire, the beer was advertised as being richer and more nourishing than ale, and was intended for porters and other heavy laborers who would find in it the strength to 
accomplish their tasks. Its color comes from roasted, unmalted barley

Stout:  A very dark, heavy, top-fermented beer made from pale malt, roasted unmalted barley, and often caramel malt. Stout was first introduced by Guinness as an extra stout version of their porter. The new stout was darker, hoppier and richer than porter, which it gradually overtook in popularity. A distinction is drawn between sweet stout and dry stout: although both are highly hopped, sweet stout is less bitter than dry stout.

Yeast: The yeast strain used to make lagers, a bottom fermenting yeast. This yeast strain settles to the bottom of the tank during fermentation. Saccharomyces Cerevisiae/Ale Yeast/Top Fermenting Yeast: The yeast strain used to make ales, a top fermenting yeast. This strain rises to the top of the tank during fermentation.

Wort: The liquid malt extract that is filtered from the mash during lautering. A sweet, amber colored, clear liquid, wort is basically food for the yeast. 

Yeast: One of the four ingredients of beer. Yeast is a single cell organism whose metabolism converts the sugars contained in the malt into  alcohol and carbon dioxide. One species, Saccharomyces cerevisiae is used to make ale, and another, Saccharomyces carlsbergensis, is used to make lager.

Zymurgy: The science of brewing beer.