Why is the brit on the eighth day?

Because the Torah commands it (Genesis 17:12). The Sages add reasons, but the day is set by the verse.

Can the brit be postponed?

Yes – if the baby is jaundiced or unwell, the brit waits until a doctor and the mohel agree he is healthy. A postponed brit is not held on Shabbat.

When is the baby named?

During the ceremony, right after the circumcision, in the prayer said over wine.

The person honoured with holding the baby during the circumcision, often a grandfather or a respected rabbi.

Brit milah (bris) – the covenant of circumcision בְּרִית מִילָה

Brit milah – “covenant of circumcision”, in Yiddish bris – is the circumcision of a Jewish boy on the eighth day of life, the sign of the covenant between God and Abraham’s descendants. The baby receives his Hebrew name during the ceremony.

The source

God commanded Abraham: “at eight days old every male among you shall be circumcised” (Genesis 17:12), and the Torah repeats it (Leviticus 12:3). The brit takes place on the eighth day even on Shabbat or Yom Kippur (Shabbat 132a), but it is postponed if the baby is not healthy – a child’s health always comes first (Yevamot 64b).

The ceremony

Performed by a mohel, trained in both the law and the procedure.
The sandak holds the baby on his knees; an honoured seat is set for Elijah the Prophet, “the angel of the covenant”.
Blessings are said by the mohel and the father, and the baby is named over a cup of wine.
A festive meal (seudat mitzvah) follows.

Sephardi and Ashkenazi customs

Ashkenazim hold a “Shalom Zachar” on the Friday night after a boy’s birth and often a “Vach Nacht” the night before the brit; Sephardim hold a gathering of learning and songs the night before (“Brit Yitzchak” or “Zohar night”). Sephardim often name a child after a living grandparent, while Ashkenazim name only after deceased relatives.

Sources

וּבֶן־שְׁמֹנַת יָמִים יִמּוֹל לָכֶם כָּל־זָכָר לְדֹרֹתֵיכֶם יְלִיד בָּיִת וּמִקְנַת־כֶּסֶף מִכֹּל בֶּן־נֵכָר אֲשֶׁר לֹא מִזַּרְעֲךָ הוּא
Genesis 17:12
וּבַיּוֹם הַשְּׁמִינִי יִמּוֹל בְּשַׂר עָרְלָתוֹ
Leviticus 12:3

Talmud and halachic sources

Talmud, Shabbat 130a–137b
Shulchan Aruch, Yoreh De'ah 260–266
Pirkei deRabbi Eliezer 29 – the chair of Elijah

Frequently asked questions

Why is the brit on the eighth day?: Because the Torah commands it (Genesis 17:12). The Sages add reasons, but the day is set by the verse.
Can the brit be postponed?: Yes – if the baby is jaundiced or unwell, the brit waits until a doctor and the mohel agree he is healthy. A postponed brit is not held on Shabbat.
When is the baby named?: During the ceremony, right after the circumcision, in the prayer said over wine.
What is a sandak?: The person honoured with holding the baby during the circumcision, often a grandfather or a respected rabbi.