Jörð is attested to in the Prose Edda and the Poetic Edda. She is Mother Earth, the goddess who is the earth herself. Her name is pronounced “ee-YURth” with a soft “th” like in “leather,” rather than a hard “th”, like in “earth.” However, as English is a Germanic language, it is completely appropriate to also call her by her English name, Earth.
Her name seems to be related to mountains and the physical terrain of the earth mass. You walk upon her, live in a dwelling constructed of her: she is inescapable, immanent, all around. She is, in many ways quite the opposite of many of the Abrahamic notions of the divine, who see the divine as necessarily outside of the world: she is the divine that is the world, herself.
Jörð is the daughter of Nótt (Night) and Annar, both primordial Jötnar. She is referred to as Frigga’s parent by the name of Fjörgyn, with another deity called Fjörgynn (the masculine version of Fjörgyn). She is the mother of Thor and another god named Meili, by Óðin.
Jörð herself is a jötunn, one of the elder race of giants. She is counted among the Asyjnur, the major goddesses of Ásgard, and she is looked to as a benevolent deity who receives veneration in modern North pagan practice. One of the distinguishing traits of the Jötnar is that they tend not to care for, and are even hostile towards, humankind. The Jötnar counted among the gods of Ásgard are those who, like the gods, care for and watch over us. Interestingly, there are said to be nine Jörð-like giantesses, one for each of the Nine Worlds. Whether Jörð has eight sisters, or whether the ancient Norse people were aware of the other planets in our solar system, or whether Jörð exists inter-dimensionally, is not known.