Kraft Singles is introduced in 1949. One of the more famous ad campaigns involved the claim that each ¾ ounce slice contained “five ounces of milk”, which makes them taste better than imitation cheese slices made mostly with vegetable oil and water and hardly any milk. The campaign was lambasted for its implications that each slice contained the same amount of calcium as a five-ounce glass of milk and also more calcium than imitation cheese slices, which eventually led to a ruling by the Federal Trade Commission in 1992 that ordered Kraft to stop making false claims in its advertising.
In the US, Kraft Singles is manufactured in regular, 2% Milk, and Fat Free. In Australia, a short-lived product called Vegemite Singles combined Kraft Singles and Vegemite.
Kraft individually wrapped “slices” are not really slices off a block, but formed separately in manufacturing. Kraft singles do however contain ingredients in common with cheddar cheese (pasteurized milk, cheese culture, salt, enzyme(s), annatto vegetable color) as evidenced in the below ingredients list from the Kraft website. Those ingredients are: milk, whey, milk protein concentrate, milkfat, sodium citrate, contains less than 2% of calcium phosphate, whey protein concentrate, salt, lactic acid, sorbic acid as a preservative, cheese culture, annatto and paprika extract (color), enzymes, vitamin d3. Contains: milk.