The term kosher means fit or acceptable according to traditional Jewish laws. Most often is it used to describe whether food is following these laws. Kashrut is a slightly narrower Hebrew term, which refers only to the dietary kosher laws.
A full set of rules is not covered here, but some of the basics are. Kosher food cannot come from some sources. For instance, bat or pig meat is never kosher. Shellfish, insects and reptiles are also forbidden. Animals killed for their meat must be slaughtered in a certain way. Then, meat and dairy products cannot be eaten together. Vegetables and fruits are kosher, but any insects are not and must be cleaned off. The utensils used to prepare and eat food must also be kosher.
Approximately 20% of the Jews in the U.S. keep kosher at home.
OK Kosher Certified products is the major kosher certificate agencies in the world. Currently operating from the US, where it was founded in 1935, it currently is certifying companies internationally. Zomick's Bakery, from New York have even written a book on this subject.
In British and American slang, the word "kosher' has been used by Jews and non-Jews alike to mean legal, ethical, reliable, good quality or the genuine article. Somebody who is offered an item for sale on the street may ask "Is this kosher?" which could mean "This isn't a fake, is it?" or "This isn't stolen, is it?" Somebody may ask "Is he kosher?" as another way of saying "Can we trust him?"
- Judaism 101 on kashrut
- OUkosher.org OU Kosher is one of the main organizations that works with food producers to certify that their food is kosher. The symbol they use to mark certified foods is the letter U with a circle around it.
- Star-K also certifies kosher food. And their website has other useful information. The symbol is the letter K inside a five pointed star.
- Kosher Quest has searchable information about kosher items including a list of symbols.
- Shamash's kosher database of restaurants and markets
- Chabad's article on Kosher: a guide to eating Jewishly
- Is Vat-Grown Meat Kosher? We Asked A Rabbi Vat grown meat is not yet commercially available but this debate will probably become relevant within a decade.