The Book of Job is the eighteenth book of the Old Testament and hence it is also the eighteenth book of Bible, despite being the first book of the Bible written down. While canonically following Esther, chronologically it takes place some time during Genesis, or shortly afterwards. The book of Job is a book of poetry, yet it still contains historical elements that concurrently make it a historical account. The book chronicles the situation of Job losing all that he had, while revealing that it was a bet concerning his faith, even in the face of his friends accusing him of a sin he may have committed. With God's permission, Satan takes away everything from Job, hoping he will curse God.
The actual author is unknown, other than the fact that the book is ultimately authored by God. There are several plausible suggestions as to who the author is, based on the character qualifications of the speakers.
One idea is that Job himself was the writer. In his dialogue, Job expressed that he wished his words were written down. Either throughout or after the book's events Job would have written down the words, writing them in poetic format for memorization.
Job's recurring theme is the constant struggle of Job, and why God in his sovereignty allows Satan to tempt him. Other themes are that human ways are not God's ways or are even opposite of how He thinks. This is seen when Job's friends incorrectly suggest that his suffering is a direct result of disobeying God. Overall in the end it is later revealed that his suffering is only temporary, and God restores him , and gives him twice as much as before. Ultimately though we question God, and wonder where he is in our lives the Book Job demonstrates that he is ultimately in control.
Job's main genre is as being poetic. Interestingly Job is an actual record of recorded conversations and quotations between Job and other people. Though Job is mainly dialogue, due to the poetic formatting of the book, and the fanciness and expression of the dialogue it is poetry.
Since Job has a clear plot, and contains exact quotes from conversations it can be considered a historical account. The first two chapters of Job also contain only a very small amount of dialogue and are written in an account form in order to convey the setting and pre-setting events.