Strained yogurt, Greek yogurt, yogurt cheese, sack yogurt, or kerned
yogurt is yogurt that has been strained to remove most of its whey,
resulting in a thicker consistency than unstrained yogurt, while
preserving yogurt's distinctive sour taste. Like many types of yogurt,
strained yogurt is often made from milk that has been enriched by
boiling off some of its water content, or by adding extra butterfat and
powdered milk. In Europe and North America, it is often made from
low-fat or fat-free milk. In Iceland, a similar product named skyr is
made.
Learn More on Wikipedia