Composition and properties
Gelatin is a mixture of peptides and proteins produced by partial hydrolysis of collagen extracted from the skin, boiled crushed horn, hoof and bones, connective tissues, organs and some intestines of animals such as domesticated cattle, chicken, pigs, and horses. Food-grade gelatin is produced mainly from two raw materials, beef skin and pig hide. [NB: the chart below says the inverse]. Photographic and Pharma grades of gelatin are generally made from beef bones, although some beef bone gelatin is used by the food industry. Gelatin is an animal protein unlike many other gelling agents used by the food industry.
Eggs in aspic
Probably best known as a gelling agent in cooking, different types and
بسم الله الرحمن الرحيم
If the gelatin is prepared by the skin and bones of the animals that are halal to eat then there is no harm in using it. However, the gelatin in which any part of pig is mixed it should be avoided as the pig is impure with all its parts. And it is not proved yet that after putting the skin etc of pig the inversion of substance (tabdeel mahiyat) takes place which is a method of purifying. After all it is better to avoid it.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.