What is Kosher? In short, they are foods that conform to Jewish dietary law. Many Jews carry varying levels of this; but it can get very complex. Below is a very basic introduction. Thank you to klbdkosher.org for sharing!
MEAT & POULTRY
As instructed in the Bible, not all animals and birds are kosher. Common animals that are kosher include: cow, goat and sheep. Common animals that are not kosher include: pig, horse, camel and rabbit. The same applies to birds. Most poultry is kosher. This includes: chicken, turkey, goose and duck.
In order for meat and poultry to be kosher there are additional requirements. These include slaughter in accordance with Jewish law and removal of blood via salting or roasting. This must all be done under strict rabbinical supervision. Retail products containing any animal or poultry derived ingredient are assumed to be non-kosher unless certified by a reputable kosher agency.
Dairy products must come from kosher animals. In countries where the source of milk is guaranteed by civil law (e.g. in the EU and USA), some Jewish authorities allow milk products without full-time kosher supervision. Some communities still require their milk to be fully supervised; and this is known as Cholov Yisroel. Cheese products do not fall under the general dairy category, and require full-time kosher supervision because rennet is often derived from an animal source.
Food that does not contain any meat or dairy ingredients is known as Pareve. Also known as “neutral”
Eggs are only kosher if they are from a kosher bird and do not contain any blood spots. Eggs are Pareve; the explanation is that they have been separated from the animal.
Kosher fish are species that have fins, and scales that are easily removed. Common examples include: salmon, tuna, sole. The scales of a sturgeon are extremely hard to remove – hence it is deemed to be not kosher. Common examples of non-kosher fish include: all shellfish, eels, shark, monkfish, huss and catfish. Roe and fish derivatives such as fish oil and gelatine must come from kosher fish.
All insects are considered strictly non-kosher. In some Jewish communities and to ensure the absence of insects; fruit and vegetables have to be thoroughly inspected and cleaned. Use of pesticides may be insufficient as these may kill the insects but not remove them.
Personally, I eat as a Vegetarian that eats fish when outside of my home, and only bring home kosher meat & poultry to cook.