First, a couple of interesting facts about the book of Esther: the longest verse in the Bible (at least the King James Version) is Esther 8:9, and in the Jewish and Protestant version God is not mentioned at all. The Catholic version is longer and does mention God.
The book tells the story of how Esther becomes a queen to the King of Persia, and in that position saves the Jews, which is also the origin of the Jewish holiday Purim.
The story involves Haman, an official in the King’s court, who takes what he sees as an offense from Mordecai, a close relative of Esther’s who raised her, into a plan to kill all the Jews in the empire. Haman apparently doesn’t know that Mordecai and Esther are related.
Historically, the closest time-frame scholars can find to be even close to the events in the book is in the 5th century BCE (or BC). But the similarities are not strong so many scholars see the book as a novella explaining Purim.
A slightly altered part of Esther 4:14 has become a favorite saying for some, part of what Mordecai tells Esther to encourage her to risk her own life to save the Jews:
Who knows? Maybe it was for a moment like this that you have been put into this position.