Short answers, pulled from the story.
Nestor was the legendary king of Pylos in Greek mythology, son of King Neleus and Chloris. He appears as a prominent secondary character in Homer's Iliad and Odyssey, respected for his age, his speaking ability, and his role as a counselor to the Greek forces at Troy.
Before the Trojan War, Nestor was an Argonaut who sailed in pursuit of the Golden Fleece, fought in the battle against the centaurs, and participated in the hunt for the Calydonian Boar. He became king of Pylos after Heracles killed his father, King Neleus, and all of his brothers.
Nestor's advice in the Iliad is respected by his listeners but frequently leads to harmful outcomes. In Book 11, he persuaded Patroclus to disguise himself as Achilles and lead the Myrmidons into battle, a decision that led directly to Patroclus's death. Scholar Karl Reinhardt argued this persuasion was contrary to what Patroclus had originally wanted.
Telemachus, the son of Odysseus, travels to Pylos to ask Nestor about his father's fate. Nestor receives him warmly and entertains him generously but cannot provide any useful information about Odysseus. Telemachus eventually urges Nestor's son Peisistratus to help him slip away without returning for more of Nestor's overwhelming hospitality.
Homer calls Nestor "the Gerenian horseman" throughout both epics. The epithet reflects Nestor's origin in Gerenia and his role leading the Pylian troops from his chariot, since he was too old to fight in single combat.
Nestor was said to have lived for three full human generations by the favor of Apollo. The god had taken years away from Nestor's mother Chloris and her brothers and granted those years to Nestor instead.