DRY

Mashing (or the enzymatic conversion of starches to sugar by mixing malted grains with warm water) is one of the main factors in determining the final sweetness in beer. Mash at a high temperature (up to 72C) and you will have a beer with sweetness. Mash at a lower temperature (down to 62C) and you will have a drier beer.

Yeast selection is also an important factor. Some yeasts can ferment more complex sugar while others just eat simple sugars and then rest. So by mashing at a relatively low temperature and selecting a yeast that can ferment a wider range of sugars, you end up with a beer with less residual sugars (and a corresponding slightly higher alcohol content).

Brewers can also create a drying sensation by mineral salts. Sodium chloride (or table salt) creates a drying sensation. Calcium sulfate (or gypsum) can also do this to a lesser degree, but it is also the main ingredient in drywall.