Whey is generally considered a by-product of the cheese making process, and almost all cheeses are drained of their whey before they are finished. Whey is formed when curds separate from the cream or milk in cheese; the liquid remaining is called whey. Whey often has a light blue color and has a thin, watery consistency.
Gjetost cheese is a traditional Norwegian cheese traditionally served for breakfast, but it can be eaten at other times of the day as well. Gjetost has a reddish-orange color and is commonly made from whey that is heated slowly until the water has evaporated and the milk sugar forms a kind of brown caramelized paste. Next, the milk or cream is added to the mixture. Gjetost cheese is almost always sold in square blocks without a rind.
Ricotta cheese, used frequently in Italian recipes and cuisine, is made from whey or, in some cases, buttermilk. Most ricotta cheese is made from the whey drained off of mozzarella or provolone, and technically is not a cheese at all because it is made from a cheese by-product. Ricotta cheese has a slightly grainy texture similar to cottage cheese, though the flavor is considerably sweeter. Ricotta cheese is most often made from whole cow's milk, but sheep's milk ricotta is produced in some areas as well.
Farmer's cheese is a bit of a catchall name for homemade cheeses that are somewhat unrefined compared to commercial cheeses. In most cases, the only ingredients used to make farmer's cheese are whole milk, buttermilk, vinegar and salt, simmered at just below 200 degrees before allowed to set. Some makers choose to separate the whey from the curds using cheesecloth or other tools, but the whey is often left in to form a creamier, softer cheese similar to the color and texture of ricotta cheese.
Feta cheese is a common cheese often produced in Greece and Israel, though it is produced all over the world and in private homes for consumption. Made from goat cheese or sheep's milk, feta cheese generally has a crumbly, white texture with a tangy taste. In some cases, the whey is strained from feta cheese, but other producers leave a certain portion in, mostly for the added water content, which creates a lighter texture. Feta cheese is often referred to as having a pickled or briny taste compared to other cheeses.