Gelatin
A gelling protein from animal collagen; halal only when the source animal and its slaughter are verified.
Why this is a critical point
Gelatin is extracted from the skin, bone, or connective tissue of cattle or pigs. When sourced from cattle, its halal status depends on how the animal was slaughtered; when sourced from pigs, it is haram without exception. Packaging rarely states the source clearly.
Halal alternative
Fish gelatin, halal-certified bovine gelatin, or plant-based agar-agar/carrageenan.