What are the dietary restrictions that some Jews follow to "keep kosher" (the laws of kashrut)?

One can find the source of the laws of Kashrut in Exodus, Leviticus, and Deuteronomy. There are four main laws, written within these books, upon which all laws are based. These rules are: "You shall not cook a kid in its mother's milk" (Exodus 23.19); "You shall set apart the ritually clean beast from the unclean" (Leviticus 20.25); "You must not eat flesh torn by beasts" (Exodus 22.30); and "You shall not eat anything that dies a natural death" (Deuteronomy 14.21).

How strictly one observes kashrut varies not only within the denominations but, like the observance of Shabbat, from family to family.

There are a number of foods that have already been predetermined by the Torah and interpreted by the rabbis as either kosher or non-kosher.

Prohibited Fowl: Bat, cuckoo, eagle, hawk, heron, kite, lapwing, ostrich, owl, pelican, stork, swan, and vulture.
Permitted Fowl: Capon, chicken, dove, duck, geese, pigeon, and turkey.

Prohibited Fish and Seafood
: Catfish, eel, porpoise, shark, whale, clam, crab, frog, lobster, octopus, oyster, scallop, shrimp, and snail.
Permitted Fish and Seafood: Anchovy, bluefish, butterfish, carp, cod, flounder, fluke, haddock, halibut, herring, mackerel, pike, porgy, red snapper, salmon, sardine, seabass, shad, smelt, sole, trout tuna, weakfish, and whitefish.

Meat restrictions: All animals that chew their cud and have a split hoof are kosher. This includes cattle, sheep, goats, and deer, and excludes horses, donkeys, camels, and pigs.
Meat must be killed according to the laws of shechitah, laws written that govern how an animal that is to be eaten must be killed.
Once a beast has been slaughtered, it must be salted properly in order to remove excess blood.

Egg restrictions: Eggs from non-kosher birds are not kosher. Eggs with bloodspots are not kosher.

There are no holidays in which the laws of kashrut are not in effect. There are a few, however, when there are extra restrictions on what you can and cannot eat. The holiday that has the most restrictions on what we can and cannot eat is Passover.

Kosher food can often be identified by the following markings that may be stamped on the packaging: