Swiss cheese is a name for a number of cheeses that resemble Swiss Emmental cheese. This is especially true for the United States and Canada. In most cases, these cheeses are made in the US or Canada, and only resemble Emmental cheese. Like Emmental, they have holes.These holes are created by the bacteria which change milk to Swiss cheese. "Propionibacterium" uses the lactic acid which is produced by other bacteria, and produces carbon dioxide gas; the gas slowly forms bubbles which makes the holes. The holes of the cheese are called the "eyes", and a Swiss cheese which does not have holes is called a "blind" cheese.