Delphi is an archaeological site and a modern town in Greece on the south-western spur of Mount Parnassus in the valley of Phocis. Delphi was the site of the Delphic oracle, most important oracle in the classical Greek world, and it was a major site for the worship of the god Apollo. His sacred precinct in Delphi was a Panhellenic sanctuary, where every four years athletes from all over the Greek world competed in the Pythian Games. Delphi was revered throughout the Greek world as the site of the omphalos stone, the centre of the earth and the universe.
Delphi is perhaps best-known for the oracle at the sanctuary that became dedicated to Apollo during the classical period. With 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. 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.
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 trance, allowing Apollo to possess her spirit. In this state she prophesied. She spoke in riddles, which were interpreted by the priests of the temple, and people consulted her on everything from important matters of public policy to personal affairs. (Don’t you love Wikipedia)