What is Malt?
Often referred to as "the soul of beer", malt gives beer its colour, malty-sweet flavour and aroma, and the sugars needed for fermentation. Malt can be produced from many different grains, but barley and wheat are the most common. During the brewing process, malt is mixed with hot water to create the mash, which leads to an enzymatic reaction called saccharification where starches contained in the malt are converted to sugar.
Malt Varieties
When developing a malt bill, brewers generally start by determining the 'base malt'. A base malt makes up the majority of all malt used in the beer, typically 70% - 100% of the malt bill. Base malts are used for their high diastatic power (i.e. how efficiently the natural starches within the malt can be converted to sugar) and have several varieties, such as 2-row, pale, spelt, maris otter, golden promise, pilsner, Vienna, Munich, and others.
A variety of specialty malts exist that are used to make a wide range of beer styles. "Specialty" is a catch-all term used to describe any non-base malt that is used in the recipe. Though specialty malt can add additional sugar, the main purpose is to alter the beer style by adding additional color and flavor not imparted by the base malt.