Colby is a cow's milk cheese. It was originally called Colby Swiss Cheddar.
Joseph F. Steinwand in 1874 developed a new type of cheese at his father's cheese factory near Colby, Wisconsin. The cheese was named after the village, which had been founded three years earlier.
An 1898 issue of the "Colby Phonograph" noted that "A merchant in Phillips gives as one of the 13 reasons why people should trade with him, that he sells the genuine Steinwand Colby Cheese." After the turn of the century Wisconsin became known as one of the great cheese producing centers in the United States.
Colby is similar to Cheddar, but does not undergo the cheddaring process. Colby is a softer, moister, and milder cheese than Cheddar because it is produced through a washed-curd process. Colby is considered semi-hard. The washed-curd process means that during the cooking time, the whey is replaced by water; this reduces the curd's acidity, resulting in Colby's characteristically mild flavor. Like most other cheeses, it takes a little more than a U.S. gallon of milk to produce just 1 pound (just over 8 liters for a kilogram) of cheese. Monterey Jack cheese is produced almost identically as Colby, but is uncolored and softer.
Longhorn is the best known style of the American Colby cheeses. ("Longhorn" cheese refers to a mild Cheddar or Colby cheese made into a long orange cylinder. Now available in both its original shape and also in rectangles and half rounds.) Colby should not be aged. Colby dries out quickly. Colby cheeses are typically sold in half-rounds. Pinconning cheese is a sharp aged relative of Colby cheese.
Because it is such a mild cheese, Colby is seldom used in cooking. It is used as a table cheese, for grating and grilling, and in snacks and salads.
Colby is sometimes mixed with Monterey Jack to produce a marbled cheese often called Colby-Jack or Co-Jack.