Cheese is a general term describing curdled milk (or cream). To curdle milk - is to separate the whey from the curds. Milk proteins (casein) are ostensibly broken in half. One half precipitates out of the milk, becoming a solid (the curds). The other half remains liquid (the whey), though it ceases to be white. The distinction between true cheese and things like cream cheese, sour cream, etc. is the way in which the milk is curdled.