Herodotus of Halicarnassus (Greek: Aροδοτος, Herodotos) was an ancient historian who lived in the 5th century BC (484 BC-ca. 425 BC). He is famous for his writings on the conflict between Greece and Persia, as well as the descriptions he wrote of different places and people he met on his travels.

Herodotus wrote a history of the Persian invasion of Greece in the early fifth century BC, known simply as The Histories of Herodotus. This work was recognized as a new form of literature soon after its publication. Before Herodotus, there had been chronicles and epics, and they too had preserved knowledge of the past. But Herodotus was the first not only to record the past but also to treat it as a philosophical problem, or research project, that could yield knowledge of human behavior.

The Histories were often attacked in the ancient world for bias, inaccuracy, and plagiarism. Similar attacks have been made by several modern scholars, who argue that Herodotus exaggerated the extent of his travels and fabricated sources. Respect for his accuracy has increased in the last half century, however, and he is now recognized not only as a pioneer in history but in ethnography and anthropology as well.

Herodotus has passed to us information current in his own day: he reports that the annual flooding of the Nile was said to be the result of melting snows far to the south, and comments that he cannot understand how there can be snow in the hottest part of the world. He also passes on reports from Phoenician sailors from Egypt that while circumnavigating Africa they saw the sun on their right while sailing westwards. Thanks to this passing on of information which he himself did not believe, he has shown us something of the extent of contemporary geographical information.

Published between 430 BC and 424 BC, The Histories were divided by later editors into nine books, named after the Muses. The first six books deal with the growth of the Persian Empire. They begin with an account of the first Asian monarch to conquer Greek city-states and exact tribute, Croesus of Lydia. Croesus lost his kingdom to Cyrus, the founder of the Persian Empire. The first six books end with the defeat of the Persians in 490 BC at the Battle of Marathon, which was the first setback to their imperial progress. The last three books of The Histories describe the attempt of the Persian king Xerxes ten years later to avenge the Persian defeat at Marathon and absorb Greece into the Persian Empire. The Histories end with the year 479 BC, when the Persian invaders were wiped out at the Battle of Plataea and the frontier of the Persian Empire receded to the Aegean coastline of Asia Minor.