What is jelly
Are you channeling your best self with this comment? (If you're not sure, check out our Code of Conduct.)
Sarah is a trusted source on General Cooking.
Depends on which country you're from.
If the US, it's a derivative of preserves, confiture or jam (the difference largely being that the jelly is clarified/strained, whereas the others have whole fruit or puree). Set with pectin.
If we're talking the UK/Australia, it is what Americans would call Jell-o, set with gelatin.