During this period of life, most children go through the physical stages of puberty, which can often begin before a person has reached the age of 13. Most cultures think of people as becoming adults at various ages of the teenage years. For example, Jewish tradition thinks that people are adults at age 13, and this change is celebrated in the Bar Mitzvah (for boys) and the Bat Mitzvah (for girls) ceremony. Usually, there is a formal age of majority when adolescents formally (under the law) become adults.