Herodotus' philosophies and work on his text, History, was seen as revolutionary at the time of its publication, as it had been among the only insights into the Persian and Greek empires. But while history remains history, the backgrounds of the authors and context are still important in understanding the importance of their work and the stance they take in the events they retell.
The question of Herodotus - a Greek historian born in the Greek city of Halicarnassus that was then under Persian control - and his bias has become an increasingly contentious issue in the realm of historical accuracy. More specifically, Herodotus could be seen as having a sort of inclination towards writing his text, History, in favor of the Greeks based on this affiliation with Greece.
His book, History, tells the story and events that unfolded throughout the Persian and Greek Empires, mainly concerning the Persian Wars. The Persian Wars were conflicts between Persia and Greece in 5th century BCE. Throughout history, it has been said that he wrote this revolutionary text on an important and early period of history as a result of his strong feelings to ensure that the events of the past were remembered. When the text and its effectiveness is described, one often alludes to how the events are rendered in a way that makes it seem that the speaker was truly participating in the battle or in the occurrence. This story telling constructs the story into something that the reader can relate history to.
But the ambiguity surrounding this idea also refers to historical accounts that Herodotus never participated in the actual battle, instead viewing it as an outsider and writing on it. Herodotus also includes speech in his renderings, speech that he came up with. The speech that he included and made up tends to be largely dramatic speeches by Greek leaders and not much speech at all coming from the Persians. Speech can be seen to build character, to build rationale, to effectively explain what, in its entirety, was playing out. Having only written on the Greeks, one can say that Herodotus built a greater and dramatized impression of the Greeks and less of an impression of the Persians. Herodotus used his personal life, upbringings, and biases and let that affect his work and how that portion of history was perceived for centuries to come.
Herodotus was widely regarded as having proven history, but some say that he didn't do it effectively. Some of his biased retelling did not account for what else happened during that same period. Without a full spectrum of the period's events students will only be learning the history he writes about, and, when that history has been even minimally altered or tampered with, one's perception of the characters and events also gets affected and becomes false.
Minimally changing people's perceptions in favor of the Greeks may have been Herodotus' goal, and throughout that period of time, many called him a liar and his books merely tales. But at the same time, many others called Herodotus an entertainer and a true prover of history. After all, he is one of the only people, albeit an outsider of the events, who brought history to paper, allowing it to be learned and expanded on for years upon years to come.