Original: According to Jewish law , when Jewish children reach 13 years of age for boys and 12 years of age for girls , they become responsible for their actions , and '' become a Bar or Bat Mitzvah '' ( English : Son ( Bar ) or Daughter ( Bat ) of the commandment ) . In many Conservative and Reform synagogues , girls celebrate becoming a Bat Mitzvah at age 12 , along with boys at 13 .
Simplified: In Judaism , a Bar Mitzvah is a Jewish boy , and a Bat Mitzvah a Jewish girl , who has turned 13 years old ( or for a girl in the Orthodox movement , 12 years old ) , and who has gone through a ceremony that represents acceptance of some responsibilities which symbolizes their coming of age .