Jewish people eat food that is primarily kosher. This is food that is blessed by a rabbi before being packaged and/or shipped. There are also other miniscule rules associated with what Jewish can and cannot eat.
The term "kosher food" refers to any foods that are made and produced according to the requirements of Jewish Law. It is only important to the extent that you are a person who follows Jewish Law and, therefore, wants to only eat kosher food.
Jewish people have to follow there food laws because it says in the bible and they are religious people ! it is one of the law within the foundation of the Jewish religion Jews follow the Torah witch has the five books of Moses from the old statement of the bible.