A bar mitzvah (literally “son of the commandments”) or bat mitzvah ("daughter of the commandments") is a ceremony that marks the transition from a Jewish child into a Jewish adult. It is usually held around a girl's 12th birthday or a boy’s 13th birthday. After reaching this age, the age of mitzvot, a Jewish teen is now responsible for his own actions.
What changes after a bar/bat mitzvah?
Other than the responsibility of writing hundreds of thank-you notes, post-bar/bat mitzvah teens can be counted in a minyan, a quorum of 10 Jews needed to pray. They are considered adults in the Jewish community, and they are required to follow all the commandments -- yep, that means fasting on Yom Kippur!
What happens at the actual bar/bat mitzvah ceremony?
The bar/bat mitzvah ceremony varies based on the congregation, the family and the skill level of the student. Usually, the teen will be called to the Torah to say the Torah blessing for the first time and will give some sort of speech relating to the Torah portion. Some students will also chant the Torah portion, chant the Haftarah or lead parts of the service.
Why should I bother?
Going through with a bar/bat mitzvah is hard work; but students learn that if they can accomplish this, they can accomplish anything. It’s a great morale-booster, and it’s an important way to join the community of Jewish adults who have all gone through the same process.