That history matters.
A bat mitzvah marks religious adulthood for a girl
Britannica explains that a bat mitzvah marks the coming of age of a Jewish girl and her acceptance of religious responsibility, often at age 12 or 13 depending on the community.
Like bar mitzvah, the core issue is obligation, not celebration.
The ceremony spread in modern times
Britannica notes that the inclusion of girls in full coming-of-age ceremony expanded in the 20th century, especially in Conservative and Reform settings.
That makes bat mitzvah an important case of modern Jewish ritual development.
The ritual often mirrors the bar mitzvah
In many communities the ceremony includes Torah or Haftarah reading, a sermon, and other leadership roles in the service.
That public role matters because it marks not only adulthood but visibility within the community.
Why it still matters
Bat mitzvah still matters because it shows how Jewish communities negotiate continuity and change while keeping commandment and public learning at the center.
The shortest accurate answer
A bat mitzvah is the Jewish coming-of-age milestone for a girl, marking religious adulthood and responsibility for Jewish obligation.