Esther is the seventeenth book of the Old Testament and the Bible. The book of Esther is unique in that the name of God is never directly mentioned. The book of Esther is the story of how a young orphaned Israelite girl from the tribe of Benjamin (Esther 2:5-7) rose from being a former prisoner-exile to Queen of Persia.
Esther first appears in book of Esther Chapter 2. Chapter two also records the good deed of Mordecai in saving the Kings life by alerting him of an assassination attempt on his life. This deed is recorded in the record books and later serves as a blessing for Mordecai in the future.
Originally named Hadassah, meaning myrtle (an evergreen shrub used for its violet flowers and for making perfume), she later became known as Esther, which is a form of the Persian word satarah, which means a star.
Esther's family had been among those of the southern kingdom of Judah, composed of the tribes of Judah and Benjamin (1 Kings 12:21) who had been conquered by the Babylonians under King Nebuchandnezzar. After the Babylonian empire was itself conquered by the Persians under Cyrus the Great, the Jews (actually, Jews and Benjamites) were permitted to return to Jerusalem: their descendants form the Jewish people today.
When orphaned at a young age, Esther was raised by her older cousin, Mordecai, who worked in the household of the Persian king (Esther 2:5-7). They apparently did not make use of the permission granted by Cyrus for the exiles to return to Jerusalem (approximate dates): 536 BC - the return from Babylon to Jerusalem 536-516 BC - the rebuilding of The Temple 478 BC - Esther became queen of Persia 473 BC - Esther saved the Jews from massacre 457 BC - Ezra went from Babylon to Jerusalem 444 BC - Nehemiah rebuilt the wall of Jerusalem
After the king divorced Vashti when she refused to appear before the people at the great banquet (Esther 1:10-12), Esther was chosen to be his wife.
Esther's role in the saving of the Jewish people came after Haman the Agagite, in effect the prime minister of Persia, managed to get a royal decree to kill all of the Jews throughout the Persian empire, which would then have included those who had returned to Jerusalem. In Chapter three Haman is honoured by the King and given a high position in the kingdom. Haman is annoyed with Mordecai because Mordecai refuses to kneel down to him. Haman's anger leads him to plot the execution of all the Jews in the kingdom. Although the original order could not be revoked according to Persian royal custom, Esther's convincing of the king to give the Jews the means and military authority to defend themselves within the Persian kingdom (Esther chapter 8) successfully averted the genocide. Also, through Esther, Haman was hanged on the gallows that he had intended to use for Mordecai (Esther chapter 7).
There is virtually no doubt that Esther was directly chosen by God to avert the destruction of the chosen people - from whom came the ancestors of Jesus Christ. To commemorate that deliverance, the Jews began the festival of Purim (Esther 9:18-32), which is still observed to this day.
Lots of this text has been taken from http://www.keyway.ca/htm2011/20111116.htm.