A megillah is a scroll, specifically referring to one of the five biblical scrolls (Song of Songs, Ruth, Lamentations, Ecclesiastes, and Esther) that are read publicly during Jewish holidays. The most well-known megillah is the Book of Esther, read during Purim, which recounts the story of the Jewish people's deliverance from a plot to annihilate them. This reading is accompanied by specific customs and laws tied to public recitation, emphasizing community and remembrance in Jewish tradition.