Quark or quarg is a type of fresh dairy product made from milk. The milk is soured, usually by adding lactic acid bacteria cultures, and strained once the desired curdling is achieved. It can be classified as fresh acid-set cheese. Traditional quark can be made without rennet, but in modern dairies small quantities of rennet are typically added. It is soft, white and unaged, and usually has no salt added.

Although quark is sometimes referred to loosely as a type of "cottage cheese", they can be distinguished by the different production aspects and textural quality, with the cottage cheese grains described as more chewy or meaty.