A hechsher (IPA: /hɛxʃəʁ/, הכשר Hebrew: "kosher approval" , plural: hechsherim) is the special certification marking found on the packages of products (usually foods) that have been certified as kosher (meaning "fit" for consumption). In Halakha (Jewish law), the dietary laws of kashrut specify food items that may be eaten and others that are prohibited as set out in the commandments of the Torah. Observant Jews generally will only eat permitted foods. 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 letters after the hechsher to denote whether the product contains meat (often denoted "Meat"), dairy (D or Dairy), neither meat nor dairy (Pareve), whether the product is Kosher for Passover because it contains no chametz (P), whether the product is pas yisroel (bread baked at least in part by a Jew), cholov yisroel (any dairy products came from Jewish owned farms), or whether the product is yoshon (lit. "old": all grain contents took root before the previous Passover).
In America, one of the best known hechsher symbols is the "OU" of the Orthodox Union based in New York City in the United States. Outside of the United States, they are less well known. They employ hundreds of rabbis as mashgichim and are generally accepted.
There are many other respected hechsher logos; examples include: Star-K based in Baltimore, Maryland, the logo of both the Johannesburg and Cape Town Beth Din used in South Africa, MK Va'ad Ha'ir based in Montreal, Canada, and Kosher Australia based in Melbourne, Australia.
The largest number of agencies are in the U.S.A. Kashrus Magazine publishes an annual guide of almost all kosher supervision agencies world-wide; its 2007 Kosher supervision Guide features 921 agencies.
Many restaurants in the centre of Jerusalem as well as many other places display these certificates. Examples of these organisations include: