CHEESE SCIENCE EXPLAINED
Cheese is essentially milk protein and fat, heavily concentrated, with much of the water removed, and with addition of salt. But it doesn't mean that cheese tastes similar to milk. Much of the cheese flavor is created by breaking down the basic ingredients of cheese by enzymes from microbes and milk itself. This process is of course controlled, but the result is nevertheless a mass of food that is slightly off. That's why some people don't like cheese, they get offended by the taste of what they perceive as rotten food. Most people however like cheese, and there are many variants of cheese to select from and enjoy.
Cheese can be made from cow milk, sheep milk, goat milk or even other types of milks. The type of animal will affect the flavor and texture of the cheese. In addition, if the animals are fed with fresh, green food, maybe containing some aromatic herbs, then the cheese will also be more flavorful. One way to tell if cheese comes from such animals is to look at its color - the more yellow it is, the more fresh veggies have been given to the animals (unless the breeders or cheese makers cheat by adding some yellow pigment to the food!).
The key ingredient in making cheese is rennet. It is extracted from cow stomach and contains an enzyme (chymosin, that is nowadays available from biotech companies) that breaks down a certain kind of protein in the milk, which essentially leads to curdling of all proteins. The advantage of rennet is that it doesn't destroy the protein and calcium "network", as an acid would do, so the cheese is given a stronger texture and also allows a good environment for other enzymes to do their job.
Once the rennet has curdled a sufficient mass of cheese, the remaining whey is drained off and the cheese is ripened by adding other enzymes. They can come from different sources and will create different flavors and textures, which explains the wide variation of cheeses available. To begin with, bacterial enzymes already present in milk (or added to it, if the milk was pasteurized) will start to break down proteins into a number of flavorful ingredients. In special cheeses, like roquefort or gorgonzola, special bacteria are added that break down proteins and fats into components that will make...well, the special kind of cheese.
In cooking, cheese is usually an add-on, either used for garnish, as a melted layer, and for adding special flavor to the dish. There are however some dishes wherein cheese is the major ingredient. One of the famous ones is cheese fondue. Originating from the Swiss Alps, cheese fondue is made of white wine, kirsch, and of course - cheese. This mixture is melted in a pot which is kept hot, and suitable for bread dipping. The reason for having wine in the cheese fondue is not only the flavor but also the acidity that prevents the cheese from becoming stringy in prolonged heat. This is a good rule of thumb to keep in mind otherwise, when a cheese-containing dish starts to "coagulate" - try adding some acid, like lemon juice or vinegar, to attempt a rescue.