Poseidon is one of the twelve Olympian deities in ancient Greek mythology, known as the god of the sea, earthquakes, and horses. He played a vital role in Greek culture, symbolizing the power of the oceans and the unpredictability of nature. As a major figure in myths, Poseidon not only influenced maritime activities but also represented the Greeks' connection to the sea, shaping their identity as seafarers and traders in the Mediterranean world.