What's a Bat Mitzvah?
Bat Mitzvah literally means “daughter of the commandments.”
A Bar, Bat, B’nai or B’not Mitzvah is the ceremonial recognition that a young person has reached the age of 13 - when he or she will begin to take on the religious privileges and responsibilities of becoming a Jewish adult.
(Bar is for a male; Bat is for a female; B’nai is for multiple boys or a mix of boys and girls; and B’not is for multiple girls).
Emily will automatically become a Bat Mitzvah when she turns 13, regardless of whether she has this Bat Mitzvah. The service will be a public recognition of this adult status.
By leading us in prayer and reading from the Torah, Emily is enabling us, her friends and family, to be together and experience the mitzvah of hearing the Torah read out loud on Shabbat.
The Bat Mitzvah party derives from the custom of serving a s'udat mitzvah ("meal celebrating the performance of a mitzvah"). It is Jewish custom to rejoice and celebrate with family and friends during this time of great happiness.