Kosher foods are foods that conform to the Jewish dietary regulations of Kashrut (dietary law) this is from Leviticus and Deuteronomy. Food that may be consumed halakaha (law) is termed Kosher,The torah only permits land animals that chew their cud and have cloven hooves. Four animals the hare, hyrax, camel, and pig are specifically identified as being forbidden as they possess one of the characteristics. The torah lists winged that may not be consumed as birds of prey. fish eatting water birds, and bats. The torah permits fish residing in the sea and the rivers only having both scales and fins.
According to rabbinical writers eggs from ritually pure animals, I can go on but the best thing to do is to go to your phone's play store and install the kosher scanner. This will help you to identify the many kosher signs and their meaning to the diet.