Q: Is it allowed to eat food, e.g. some candies, in which animal gelatin is used?

A: Gelatin's being ḥalāl or ḥarām depends on the materials from which it is obtained. Vegetable gelatin is ḥalāl. Regarding the gelatin which is obtained from the bone of a religiously edible animal (like a cow) which has not been ritually slaughtered, then if the external surface of the bone is purified before changing it into gelatin, it is pure and ḥalāl. But the gelatin produced from the skin of such an animal or that is made from the parts of a religiously non-edible animal is najis and ḥarām. However, if there are two - ḥalāl and ḥarām - types of gelatin and you do not know the one you are going to eat belongs to which group, it is ruled to be ḥalāl.