Wiki - "The name Delphois comes from the same root as δελφύς delphus, "womb" and may indicate archaic veneration of Gaia, Grandmother Earth, and the Earth Goddess at the site. Apollo is connected with the site by his epithet Δελφίνιος Delphinios, "the Delphinian." The epithet is connected with dolphins (Greek δελφίς,-ῖνος) in the Homeric Hymn to Apollo (line 400), recounting the legend of how Apollo first came to Delphi in the shape of a dolphin, carrying Cretan priests on his back. The Homeric name of the oracle is Pytho (Πυθώ).
The Delphi site is located in lower central Greece, on multiple plateau/terraces along the slope of Mount Parnassus, and includes the Sanctuary of Apollo, the site of the ancient Oracle. This semicircular spur is known as Phaedriades, and overlooks the Pleistos Valley. Southwest of Delphi, about 15 km (9.3 mi) away, is the harbor-city of Kirrha on the Corinthian Gulf.
Delphi is perhaps best-known for the oracle at the sanctuary that became dedicated to Apollo during the classical period. According to Aeschylus in the prologue of the Eumenides, it had origins in prehistoric times and the worship of Gaia. In the last quarter of the 8th century BC there is a steady increase of artifacts found at the settlement site in Delphi, which was a new, post-Mycenaean settlement of the late 9th century. Pottery and bronze work as well as tripod dedications continue in a steady stream, in comparison to Olympia. Neither the range of objects nor the presence of prestigious dedications proves that Delphi was a focus of attention for worshipers of a wide range, but the strong representation of high value goods, found in no other mainland sanctuary, certainly encourages that view.
Delphi became the site of a major temple to Phoebus Apollo, as well as the Pythian Games and the famous prehistoric oracle. Even in Roman times, hundreds of votive statues remained, described by Pliny the Younger and seen by Pausanias. Supposedly carved into the temple were three phrases: γνωθι σεαυτόν (gnōthi seautón = know thyself) and μηδέν άγαν (mēdén ágan = nothing in excess), and Εγγύα πάρα δ'ατη (engýa pára d'atē = make a pledge and mischief is nigh), as well as a large letter E. Among other things epsilon signifies the number 5. Plutarch's essay on the meaning of the “E at Delphi" is the only literary source for the inscription. In ancient times, the origin of these phrases was attributed to one or more of the Seven Sages of Greece, though ancient as well as modern scholars have doubted the legitimacy of such ascriptions. According to one pair of scholars, "The actual authorship of the three maxims set up on the Delphian temple may be left uncertain. Most likely they were popular proverbs, which tended later to be attributed to particular sages."
Another legend held that Apollo walked to Delphi from the north and stopped at Tempe, a city in Thessaly to pick laurel, a plant sacred to him (generally known in English as the bay tree). In commemoration of this legend, the winners at the Pythian Games received a wreath of laurel (bay leaves) picked in the Temple. The Temple of Apollo, viewed from below the eastern end. View of the mountain-top stadium of the Delphi sanctuary, used for the Pythian Games. The stone steps/seats at right were added under the Romans.
The priestess of the oracle at Delphi was known as the Pythia. Apollo spoke through his oracle, who had to be an older woman of blameless life chosen from among the peasants of the area. The sibyl or prophetess took the name Pythia and sat on a tripod seat over an opening in the earth. When Apollo slew Python, its body fell into this fissure, according to legend, and fumes arose from its decomposing body. Intoxicated by the vapors, the sibyl would fall into a trance, allowing Apollo to possess her spirit. In this state she prophesied. It has been postulated that a gas high in ethylene, known to produce violent trances, came out of this opening, though this theory remains debatable. While in a trance the Pythia "raved" - probably a form of ecstatic speech - and her ravings were "translated" by the priests of the temple into elegant hexameters. People consulted the Delphic oracle on everything from important matters of public policy to personal affairs. The oracle could not be consulted during the winter months, for this was traditionally the time when Apollo would live among the Hyperboreans. Dionysus would inhabit the temple during his absence.