Dill (Anethum graveolens) is a feathery, aromatic herb with a grassy, slightly sweet flavor and a mild licorice-like undertone, native to Southern Europe and Western Asia. Both the fresh or dried leaves (sometimes called "dill weed") and the dried seeds are used in cooking, but they taste different: the leaves are mild and grassy, while the seeds are more concentrated, closer to caraway.
Dill leaves are a staple of Scandinavian and Eastern European cooking - gravlax, potato salads, and pickles - and also appear in Indian curries, chutneys, and lentil-based dishes. They pair especially well with cucumbers, yogurt, sour cream, and lemon, and are usually added near the end of cooking to preserve their delicate flavor; the seeds are more common in pickling brines and baking.