Swiss cheese is the generic name in Australia, New Zealand, Canada, United States and Serbia, for several related varieties of cheese, all of which resemble the Swiss Emmental. Some types of Swiss cheese have a distinctive appearance, as the blocks of the cheese are riddled with holes known as "eyes". Swiss cheese has a piquant, but not very sharp taste.
Three types of bacteria are used in the production of Emmental cheese: Streptococcus salivarius subsp. thermophilus, Lactobacillus (L. helveticus or Lactobacillus delbrueckii subsp. bulgaricus), and Propionibacter (P. freudenreichii or P. shermani). In a late stage of cheese production, the Propionibacter consumes the lactic acid excreted by the other bacteria, and releases carbon dioxide gas, which slowly forms the bubbles that develop the eyes. Swiss cheese without eyes is known as "blind."
In general, the larger the eyes in a Swiss cheese, the more pronounced its flavor; this is because the same conditions that lead to large eyes—longer aging or higher temperatures—also allow the bacteria and enzymes to produce a stronger flavor. This poses a problem for makers of pre-sliced Swiss cheese, the most popular category in the United States. Cheese with large eyes doesn't slice well, sometimes coming apart in mechanical slicers. This costs time and money and is one reason why US manufacturers usually produce a product less aged and flavorful than imported cheeses of the same style.
Baby Swiss is another related cheese, often found in the US. Made by substituting water for the milk's whey to slow bacterial action, Baby Swiss cheese has smaller holes and a milder flavor. Baby Swiss is often made from whole milk.
Lacy Swiss is a further variety of US small hole Swiss cheese made with low fat milk.
The largest manufacturer of Swiss cheese in the world is Brewster Dairy, located in Brewster, Ohio.