The levels of kashrut (keeping kosher) observed vary greatly, with Orthodox Jews maintaining the strictest standards. Orthodox Jews tend to eat only foods with reliable Orthodox kosher certification. In addition, they will only eat in kosher restaurants or accept invitations from people who maintain kosher kitchens.
In general, Conservative and Reform Jews may be more lenient in their observance of kashrut. Some will buy products without kosher certification as long as they do not find non-kosher ingredients on the ingredient list. Some will eat food cooked in a non-kosher restaurant or home, as long as the meal does not contain non-kosher meat.
Generations of Jews going back at least 3,000 years have followed the laws of kashrut, or Jewish Dietary Laws. And keeping kosher has been one of the most distinctive practices followed by Jews throughout their history. Nevertheless, today the majority of Jews in America do not observe kosher laws.
Some Jews today consider Jewish Dietary Laws to be ancient health regulations that are no longer necessary as a result of modern methods of food preparation. Others are not knowledgeable about kosher laws. And others yet, who may view Jewish Dietary Laws as important and who may have knowledge of them, may chose not to observe them because of the added expense and inconvenience their observance can entail.