During a Jewish bar mitzvah Torah service, the Torah scroll itself is called a sefer Torah.
The Hebrew phrase sefer Torah means “book of the Torah,” although the object is a handwritten scroll rather than a bound book. It contains the Five Books of Moses written in Hebrew on parchment by a specially trained scribe known as a sofer. The scroll is mounted on wooden rollers, commonly called atzei chaim, or “trees of life.”
At a bar mitzvah, the celebrant may be called to the Torah, recite blessings, and chant a designated passage from the sefer Torah. The scroll is handled with great care because Jewish tradition treats it as a sacred text. Readers commonly use a yad rather than placing a finger on the parchment.
A sefer Torah is not the same as a siddur, which is a prayer book, or a machzor, which is a prayer book for major festivals. A Megillah usually refers to a scroll of one of the biblical festival books, especially Esther.