In Orthodox Judaism, a Jewish girl traditionally becomes a bat mitzvah at age 12.
Bat mitzvah means “daughter of commandment.” The age reflects the traditional Jewish understanding that girls assume religious responsibility at 12, while boys traditionally do so at 13 as a bar mitzvah. In many communities, the milestone is marked with prayer, Torah study, a synagogue celebration, or a family gathering.
Practices vary among Jewish movements. In Conservative and Reform communities, girls may celebrate at 13 and may read from the Torah or lead parts of a service. Bat mitzvah is therefore both an age-based religious status and, in modern usage, the ceremony or celebration associated with reaching it. It should not be confused with a wedding or with confirmation, which is a separate Jewish educational ceremony.