Swiss cheese is a name for a number of cheeses that are like Swiss Emmental cheese. This name is mostly used in the United States and Canada, and in most cases, the cheeses are made there and are not from Switzerland. Like it, they have holes, which are made by the bacteria that change milk into Swiss cheese. Propionibacterium uses the lactic acid that is made by other bacteria, and it gives off a gas called carbon dioxide. This slowly forms bubbles that become the holes. The holes in the cheese are called the "eyes", and a Swiss cheese that does not have holes is called a "blind" cheese.
Most often, Swiss cheeses with larger eyes have a better taste, as the same things that make the eyes bigger also make the taste of the cheese better. These include longer time and more warmth as the cheese is formed.
Emmental cheese has been produced in France, Germany, and Austria for a long time. This is why the names Emmental and Swiss Cheese can be used for kinds of cheese that are not made in Emmental in Switzerland but are made the same way.