Answer:
Eight days after a boy is born, he is circumcised and named - the traditional way of bringing him into the community. The ceremony is accompanied by a festive meal in which friends and family participate.
Some, but not all, Jews mark the birth of a girl with a simchat bat - a party/festive meal which can take place any time following the birth, as convenient for the parents. The naming of a girl traditionally takes place in the synagogue, on a Monday, Thursday or Saturday (Sabbath) following the birth.