Jelly is a sweet or savoury food gel, usually made through the addition of gelatin or pectin. Sweet food gels include gelatin desserts such as Jell-O and blancmange or fruit jam. Savoury food gels include aspic or plain gelatine. Vegetarians & Vegans make jelly not with gelatine (which comes from cows), but with agar (which comes from seaweed) which comes as crystals into which you pour water.