Originally, the expression r'w was used for the sun's disk, just as itn was in later times. The development into the name of the sun god himself appears to have been secondary, with the sun as a heavenly body being regarded as the stellar manifestation of the divine force Re.
The earliest evidence of Re as the name of a divinity dates from the time of Djoser, where we find the personal name Hesi-re. It is unclear whether there were other theophorous personal names for private individuals before then, nor does the god Re yet appear in royal names from the Early Period (the royal name Re-neb from the 2nd Dynasty should probably still be read as 'lord of the sun').
As far as the endurance and intensity of his worship is concerned, Re was a very important, if not the most important, divinity in ancient Egypt. He was not only the object of theological speculation and cultic worship, but as the national god he was also very important in the royal dogma. His most important cult centre was Heliopolis (On), but as the cosmic universal god Re was worshipped throughout Egypt. In representations he is shown as a falcon-headed human with a sun disk and uraeus, or in royal regalia with crown and sceptres. His skin and limbs were thought to be made of gold, just like the splendour of the sunlight. In his nocturnal form Re was depicted with a ram's head, in which the pun on the concept of ba (written with a ram-headed hieroglyph) must not be overlooked.
As a cosmic god, Re had a universal effect; his daily appearance affected all of creation, the maintenance and order of which was his responsibility. He is a universal world god, and his course determined the fate of humans. As an androgynous primeval god, Re was given the epithet 'who was created out of himself'. Even before heaven, earth and life itself existed, Re existed. Through his link with Atum, Re as Atum-Re was a god who accomplished the creation of heaven, earth, gods and men at the beginning of the world. As a creator god Re also took care of the continuity of creation through his daily appearance; every sunrise was a symbol of a new beginning and a reactualization of 'the first time'.
Just like the terrestrial king, Re performed the office of king of the gods. He ruled from his solar bark, surrounded by his entourage. Re also exercised absolute dominion in the hereafter. Re could count on supportive forces such as Hu (the creative word), Sia (wisdom) and Heka (creative force). As the 'Lord of Maat', Re functioned as the foreman of the Divine Tribunal and was considered to be a fair and impartial judge. The terrestrial rule of the king was closely linked with the divine rule of Re, who in a golden past had once ruled on earth himself. During the 4th Dynasty, the name of Re was included in the royal titulary and the ideology of the king as the son of Re gradually developed. After the Old Kingdom, the significance of Re as a royal and national god remained; the kingship was regarded as given to the king by Re and supported by Re; times of political unrest were interpreted as the monarchy ruling 'without Re' or Re turning his face away.
After he died, the king expected to join Re in the solar bark and participate in the divine life. In the afterworld, the king is a servant of Re, but he could also be seen as Re himself, as well as the one on whom Re depends for his regeneration. The desire to join the solar bark after death and share in the divine regeneration gradually became the wish of 'ordinary' Egyptians, too; after all, the arrival of the solar bark meant life and breath in the underworld. The deceased could even threaten to withhold offerings and breath from the sun god if he should be unwilling to provide the desired gifts. Although Re was king of the underworld, he was also perceived as dependent on the deceased, who help him to conquer his enemies.
The rising of the sun was mythically portrayed by the birth of the (child) sun god out of the goddess Nut or a different mother goddess, or by his appearance as Khepri from the primeval waters of Nun. His daily appearance in the eastern horizon was greeted by jubilating baboons, after which Re, supported by various divine forces, began his journey across the sky. In the evening, Re, now in his manifestation as old man Atum, is swallowed up again by Nut/Nun. His descent in the west was identified with death and at the same time understood as a transitional phase to a new beginning. During the night, Re travelled through the realm of the dead to be born again in the east the next morning. This cycle repeated itself indefinitely, despite the opposition of Re's most important enemy, Apophis, who tried to halt the solar bark. The victory over Apophis meant the preservation of the order of creation and the continuity of existence, both 'in heaven' and 'on earth'.