A special certification marking that shows which products are certified kosher.

To assist Jewish consumers, rabbinic authorities produce and regulate their own hechsherim. It is usually Orthodox rabbis who assume the jobs of mashgichim (singular: mashgiach, "supervisor"). This means that they will "supervise" the products and processes that manufacture kosher food to ensure compliance with the required standards. The mashgiach will allow the manufacturer to apply a hechsher to the packaging of the product only if found to contain only kosher ingredients and produced in accordance with Halakha. The rabbi may also apply additional words or letters after the hechsher to denote whether the product contains meat, dairy, neither meat nor dairy, whether the product is Kosher for Passover because it contains no chametz (leavening agents), whether the product is pas yisroel (bread baked at least in part by a Jew), or cholov yisroel (any dairy products came from Jewish owned farms).

The marking is also commonly found on items not meant for consumption, such a cleaning products.

Due to differences in kashrut standards held by different organizations, the hechsheirim of certain Jewish authorities may at times be considered invalid by other Jewish authorities; the certification marks of the various rabbis and organizations are too numerous to list, but one of the most commonly used in the United States of America is that of the Union of Orthodox Congregations, who use a U inside a circle, symbolizing the initials of Orthodox Union. Another common symbol is a K inside a circle with is the OK Kosher Certification organization. A single K is sometimes used as a symbol for kosher, but since many countries do not allow letters to be trademarked (the method by which other symbols are protected from misuse), it only indicates that the company producing the product claims that it is kosher and is not reliable.

Many of the certification symbols are accompanied by additional letters or words to indicate the category of the product, according to Jewish religious law; the categorization may conflict with legal classifications, especially in the case of food which Jewish religious law regards as dairy, but legal classification does not.

Classifications -

• D: Dairy
  
• DE: Dairy equipment – used when dairy isn’t present in a food but it was run on equipment where dairy is run. For the most stringent this makes it dairy, for the less stringent it can be eaten with meat.
• M: Meat, including poultry
• Pareve: food which is neither meat nor dairy. The full word is always used.
• P: Passover-related (P is never used for Pareve)