When Avram entered into a Covenant with God, as described in the 17th chapter of Genesis, God commanded him to circumcize himself and all the males in his household, and all those who would descend from him on the eighth day of life, as a sign of the Covenant. Ever since, Jews have circumcised their baby boys on the eighth day of life as they welcomed them into the Covenant of Israel. Boys are given their Hebrew names at this time, because the account of the covenant between Avram and God in chapter 17 of Genesis is followed by that of God changing Avram's name to Avraham (Abraham).
Circumcision has always loomed large in the Jewish psyche. It is a foundation ritual for which Jews have often times in history risked their lives to fulfill and which oppressors were often quick to outlaw in an attempt to destroy Judaism. It continues as a powerful ritual of continuity.
Circumcision is a minor operation in which the foreskin of the baby boy's penis is removed by a certified and experience mohel. The operation is most often performed in the home amidst a gathering of friends and family and there is a liturgy which accompanies the ceremony. The prophet Elijah is an honored guest, symbolically, in the hope that this child will grow to be the messiah who will redeem Israel. Indeed, a chair is set aside for the prophet, in the hopes that he will make an appearance to welcome the child. The sandek (stepfather) is the person who is honored with holding the child for the ceremony.
Circumcision is also required for conversion to Judaism. Those who have already been circumcised undergo a symbolic circumcision in which a drop of blood is drawn for the sake of entering the Covenant. This is known as tipat-dam.
There is no physical equivalent of circumcision for girls. To attempt anything physically would be forbidden by Jewish law as mutilation of the body. However, in the past two decades, many beautiful covenant ceremonies have been developed for girls to welcome them into the Covenant between God and Israel. Baby girls are given their Hebrew names at this time. For more on birth rituals, click here.