Creation ex nihilo, out of nothing, is the doctrine that God brought the universe into being without any pre-existing material, so that God alone is uncreated and everything else depends on God for its existence not only at its beginning but at every moment. It is the standard position of Judaism, Christianity and Islam, and it separates them from the many cosmogonies in which a deity shapes material already there.
Whether it is stated in scripture is disputed. Genesis 1:1-2 can be read as creation from nothing or as the ordering of a formless waste and a deep that are already present; the Hebrew syntax is genuinely open, and modern translations divide between "In the beginning God created" and "When God began to create". The earliest text usually cited as explicit is 2 Maccabees 7:28, and Romans 4:17 and Hebrews 11:3 are read in this sense in Christian tradition. Historians of doctrine generally hold that the formulation was worked out in the second century CE, by writers such as Theophilus of Antioch and Irenaeus, and worked out specifically against Platonist accounts in which matter is eternal and against Gnostic accounts in which the shaping of it is the work of a lesser and inferior being. Some scholars argue for an earlier Jewish version; the question turns on how a small number of contested texts are read.
The doctrine does identifiable work. It makes matter good, since God made it, which is the point of the second-century polemic. It makes creation free rather than necessary, distinguishing it from emanation, in which the world flows from God as light from a lamp and could not have been otherwise. It denies any independent principle limiting God. And it grounds continuous conservation: the world does not merely start but is held in being.
The rivals are still live within the theistic traditions. Emanationist schemes in Neoplatonism and in Islamic philosophy, Ibn Sina's necessary procession from the Necessary Existent, were attacked by al-Ghazali precisely because they made the world eternal and its production necessary. The eternity of the world was defended by Aristotle and by Muslim and some Christian philosophers, and Aquinas took the notable position that reason cannot demonstrate that the world had a beginning, which is known only from revelation, while creation in the sense of total dependence can be argued philosophically whether or not there was a first moment. Latter-day Saint theology rejects creation from nothing outright, holding matter and intelligence to be eternal and organised rather than made, one of the clearest doctrinal breaks between it and historic Christianity.