Urtica dioica, often known as common nettle, burn nettle, stinging nettle or nettle leaf, or just a nettle or stinger, is a herbaceous perennial flowering plant in the family Urticaceae. Originally native to Europe, much of temperate Asia and western North Africa, it is now found worldwide. The species is divided into six subspecies, five of which have many hollow stinging hairs called trichomes on the leaves and stems, which act like hypodermic needles, injecting histamine and other chemicals that produce a stinging sensation upon contact.

The Urticaceae are a family, the nettle family, of flowering plants. The family name comes from the genus Urtica. The Urticaceae include a number of well-known and useful plants, including nettles in the genus Urtica, ramie, māmaki, and ajlai.