Apollo is the son of Zeus and the Titaness Leto, twin brother of Artemis (goddess of the hunt and the moon). His birth was itself dramatic: Hera, jealous of Leto's pregnancy by Zeus, forbade any land to give Leto shelter for her birth. Only the floating island of Delos — technically not "land" — provided refuge. Apollo was born on Delos, which thereafter became one of his most sacred sites, a panhellenic sanctuary visited by pilgrims from across the Greek world.
Apollo has no clear pre-Greek origin — unlike Hecate (Anatolian) or Dionysus (possibly Thracian), Apollo appears to be a genuinely Greek creation, though some scholars have proposed connections to Near Eastern solar or archer deities. He is one of the most thoroughly Olympian of the gods — his domains (light, reason, music, prophecy) represent the highest aspirations of Greek civilisation, which is why he became the god most associated with the Greek ideal of kalokagathia: the beautiful and the good as a unified excellence.
He is depicted as the ideal of male beauty — young, beardless, perfectly proportioned, radiantly handsome. His most famous ancient statues — the Apollo Belvedere, the Kouros figures, the Apollo of Piombino — established the aesthetic standard that Western art returned to for two thousand years. The body of Apollo is itself a theological statement: perfection of form is an expression of divine truth. To be beautiful, in the deepest Greek sense, is to be aligned with the logos — the rational principle that structures the cosmos.
His primary cult centres were Delos (his birthplace) and Delphi (his great oracle on the slopes of Mount Parnassus). Delphi was understood as the omphalos — the navel of the world, the point where the divine and human most directly intersected. Apollo's temple there bore the famous maxims: Know thyself (γνῶθι σεαυτόν) and Nothing in excess (μηδὲν ἄγαν) — the two principles that Socrates, Plato and the entire Greek philosophical tradition took as their foundation.