Hechsher refers to the special marking found on the packages of products that have been certified as Kosher. OU is an example of a Hechsher - Circle U stands for Orthodox Union and Pareve means the product does not contain milk or meat. For a comprehensive list of Kosher/Hechsher symbols visit the link below. Kosher foods are certified Kosher when any of the symbols are found in the package and foods are identified Kosher with these symbols. http://www.jewishcooking.org/kosher-symbols.html