The Fast of Esther, known as Ta'anit Ester, is observed by Jews worldwide on Purim eve, specifically on the 13th day of the month of Adar. This minor fast commemorates the actions of Esther, the Jewish wife of Persian king Ahasuerus, who fasted for three days to save her people from annihilation at the hands of the royal vizier Haman. The fast is observed from dusk until dawn and is characterized by lenient laws, exempting those who are ill, pregnant, or nursing. The date may shift if it falls on a Saturday, in which case it is observed on the preceding Thursday, as fasting on Shabbat is generally forbidden. The Fast of Esther serves as a reminder of the historical struggles faced by the Jewish people and is linked to the battle preparations of warriors in ancient times.