Hermes is the son of Zeus and Maia, a daughter of Atlas. Along with Iris, he is a messenger of the gods. He is a god of merchants, thieves, shepherds and travelers, among other things. He is usually described in later myths as wearing winged sandals, a winged helmet and his Caduceus.
A masterful thief, Hermes stole the sacred cattle of Apollo before he was even a day old. He created the first lyre from a tortoise shell as well. Apollo protested and Zeus, who had been watching the whole thing, ordered Hermes to return the cattle. At this point, Hermes took out his lyre and began to play. After hearing the beautiful music, Apollo offered to exchange the lyre for the herd of cattle, and Hermes agreed.
There is a graver side to Hermes as well. It was his task to guide the dead to the underworld, as well as to deliver dreams to sleeping.
During the Trojan War, a disguised Hermes led Priam to Achilles' tent in order to retrieve Hector's body. In the Odyssey, Hermes warns Odysseus about Circe, and gave him a plant, which would counteract the witch's spells. He was also sent by Zeus to order Calypso to allow Odysseus to leave her island.
The Romans identified Hermes with Mercury, a god of the corn trade.