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.