Brit milah (Hebrew: בְרִית מִילָה [bə'rīt mī'lā] literally: "covenant [of] circumcision"), also berit milah (Sephardi), bris milah (Ashkenazi pronunciation) or bris (Yiddish) is a religious ceremony within Judaism to welcome infant Jewish boys into a covenant between God and the Children of Israel through ritual circumcision performed by a mohel ("circumciser"), on the eighth day after birth unless health reasons force a delay, in the presence of family and friends, followed by a celebratory meal (seudat mitzvah).

Biblical origin
According to Jewish tradition, the original form of circumcision practiced by Jews has traditionally existed since the time of Abraham. The rite of milah, initially consisted of cutting off only the tip of the foreskin, the part that extends past the glans in the normal male infant.

History
As stated in the above : "God [then] said to Abraham, 'As far as you are concerned, you must keep My covenant - you and your offspring throughout their generations. This is My covenant between Me, and between you and your offspring that you must keep: You must circumcise every male. You shall be circumcised through the flesh of your foreskin. This shall be the mark of the covenant between Me and you. 'Throughout all generations, every male shall be circumcised when he is eight days old. [This shall include] those born in your house, as well as [slaves] bought with cash from an outsider, who is not your descendant. [All slaves,] both houseborn and purchased with your money must be circumcised. This shall be My covenant in your flesh, an eternal covenant. The uncircumcised male whose foreskin has not been circumcised, shall have his soul cut off from his people; he has broken My covenant."
Brit milah is considered to be so important that should the eighth day fall on the Sabbath, actions that would normally be forbidden because of the sanctity of the day are permitted in order to fulfill the requirement to circumcise.

Reason
The name of Kvatter among Ashkenazi Jews is for the person who carries the baby from the mother to the father, who in turn carries him to the mohel. This honor is usually given to a couple without children, as a merit or charm that they should have children of their own. The origins of the term may simply be a corruption of "Gevatter", a German word for godfather[3], but it is also said to be a Yiddish erroneous combination of the words "Kavod" ("honor" in Hebrew) and "Tier" ("door" in Yiddish), meaning "The person honored by bringing the baby". Another Meaning is a mix of Hebrew and Yiddish. Kvatter means like the father. The traditional custom is to honor as the Kvatter a young newly-wed couple (without children of their own yet) as a merit for having a baby. The young woman (Kvatterin) carries the baby from the mother and then hands it over to her husband.

Kvatter
Less commonly practised, and more controversial, is metzitzah b'peh, alternately spelled mezizah, or oral suction, He tells the story, that a student of the Chasam Sofer - Rabbi Elazer Hurvitz, The author of responsa Yad Elazer and Chief Rabbi of Vienna at the time, (The incident is mentioned in responsa 54)- needed the ruling in defense of a governmental attempt to ban bris milah completely if it included Metztitzah b'peh, because of the concern of spreading disease to the baby. He therefore asked the Chasam Sofer to give him permission to do Brit milah without metzitzah b'peh and when he presented the defense in court they erroneously recorded his testimony to mean that the Chasam Sofer stated it as a general ruling. He then adds, "Nevertheless it is my opinion that the Chasam Sofer never even wrote this letter. It is a forgery, in my opinion, and even if the letter was written by the Chasam Sofer he certainly didn't state it as a general ruling, given that it was not printed in his book of halachic responsa, as was the custom with all halachic rulings intended for the public." Included in Ma'areches Hametzitah is a pronouncement by several hundred noted Hungarian and Russian Rabbis not to change the procedure.

Metzitzah
Metzitzah b'peh was implicated in the transfer of herpes from mohels to eight Israeli infants, one of whom suffered brain damage.

Medical controversy
In three studies done in Israel, Canada, and the USA, by Rabbi Sinai Schiffer of Baden, Germany, states that he is possession of letters from 36 major Russian (Lithuanian) rabbis that categorically prohibit Metzitzah with a sponge and require it to be done orally. Among them is Rabbi Chaim Halevi Soloveitchik of Brisk. It is interesting that of all the students of Rabbi Yosef Dov Soloveitchik and the many times he was asked to be sandek, only Rabbi Schachter seems to remember this prohibition.

By tube
A Brit milah could be circumvented with Dam Brit, or foregone altogether with a Milah L'Shem Giur:

Conversion and exceptions
If a boy is born prematurely or has some other serious medical condition the Brit is generally postponed. The brit may only take place when a doctor or the parents deem the child healthy enough.
Additionally, the Talmud explicitly notes that a male child is relieved of his responsibility to undergo circumcision if he has had three older brothers die due to complications from the procedure. This is mentioned specifically in the context of some sacrifices in which a priest was prohibited from participating if he was uncircumcised for this reason.

Medical considerations
Medical circumcision alone, in the absence of the brit milah ceremony, does not fulfill the requirements of the mitzvah. In the case of a Jew who was circumcised outside of a brit milah, or an already-circumcised convert, the mohel draws a symbolic drop of blood from the penis.
Hatafat dam brit (heb. דם ברית "Drop of the blood [of the] Covenant") refers to the fulfillment of the mitzvah of a brit milah.

Blood
There are reasons not to perform a circumcision when a man has converted to Judaism. A circumcision is not possible if a convert was already circumcised prior to conversion, or if he has a medical condition (such as hemophilia) which would cause a circumcision to potentially endanger his life. In these situations, a brit milah cannot be performed, and instead a single drop of blood is extracted, in a practice called hatafat dam brit (Heb. הטפת דם ברית).

Role in conversion
A Milah L'shem giur is a "Circumcision for the purpose of conversion". In Orthodox Judaism, this procedure is done by adoptive parents for adopted children who are being converted as part of the adoption. The conversion of an infant is valid in both Orthodox and Conservative Judaism until the boy reaches the age of 13. At that time he has the option of renouncing his conversion and Judaism, and the conversion will then be considered invalid. He must be informed of his right to renounce his conversion if he wishes. If he does not make such a statement it is accepted that the boy is halakhically Jewish. Orthodox rabbis will generally not convert a non-Jewish child raised by a mother who has not converted to Judaism.
Where the procedure was performed but not followed by immersion or other requirements of the conversion procedure (e.g., in Conservative Judaism, where the mother has not converted), if the boy chooses to complete the conversion at Bar Mitzvah, a Milah l'shem giur performed when the boy was an infant removes the obligation to undergo either a full brit milah or hatafat dam brit.

• It does not have to be performed on a particular day.
  The ceremony does not override and is not performed on Shabbat or Jewish Holidays.
  In Orthodox Judaism, there is a split of authorities on whether the child receives a Hebrew name at the Brit ceremony or upon immersion in the Mikvah. According to Zichron Brit LeRishonim, naming occurs at the Brit with a different formula than the standard Brit Milah. The more common practice among Ashkenazic Jews follows Rabbi Moshe Feinstein, with naming occurring at immersion. Milah l'shem giur
  According to the Hebrew Bible, it was "a reproach" for an Israelite to be uncircumcised (Joshua 5:9.) The name arelim ("uncircumcised" [plural]) is used opprobriously, denoting the Philistines and other non-Israelites (I Samuel 14:6, 31:4; II Samuel 1:20) and used synonymously with tameh (unclean) for heathen (Isaiah 52:1). The word arel ("uncircumcised" [singular]) is also employed for "unclean" (Leviticus 26:41, "their uncircumcised hearts"; compare Jeremiah 9:25; Ezekiel 44:7,9); it is even applied to the first three years' fruit of a tree, which is forbidden (Leviticus 19:23).
  However, the Israelites born in the wilderness after the Exodus from Egypt were not circumcised. Joshua 5:2-9, explains, "all the people that came out" of Egypt were circumcised, but those "born in the wilderness" were not. Therefore Joshua, before the celebration of the Passover, had them circumcised at Gilgal specifically before they entered Canaan. Abraham, too, was circumcised when he moved into Canaan. The opinion ascribed to Joshua contradicts the fact that in Exodus 4:26, Moses and his wife did not know about circumcision.
  Deuteronomy 10:16 says: "Circumcise the foreskin of your heart," suggesting that ethical acts (among people) are as important as spiritual acts (between people and God). The prophetic tradition emphasizes that God expects people to be good as well as pious, and that non-Jews will be judged based on their ethical behavior. Thus, Jeremiah 9:25-26 says that circumcised and uncircumcised will be punished alike by the Lord; for "all the nations are uncircumcised, and all the house of Israel are uncircumcised in heart."
  
  Social context
  
  Recent views
  The Oxford Dictionary of the Jewish Religion (ed. R.J. Zwi Werblowsky and G. Wigoder. Oxford University Press, 1997, page 161) says that at the time of the Syrian-Greek occupation, "periah" the laying bare of the glans, was added to the original rite to make it impossible for men to "undo" their circumcision. Others claim that there is no basis for this view in classical rabbinic sources, which state that the "extended" form of circumcision, including metzitzah as well, was introduced at Mount Sinai. This opinion is brought in the responsa of the Maharam Schick - Rabbi Moshe Schick- Orech Chaim 152 & Yoreh Deah 242, Shailos and Teshuvas Yehudah Ya'aleh - Rabbi Yehuda Assad, Sdei Chemed - Rabbi Chaim Chizkiyahu Midini, Shailos and Teshuvos Binyan Tzion - Rabbi Yaakov Etlinger - Vol 1:23 & 24, all of them of blessed memory.
  
  Historical view
  The anti-circumcision movement has not made significant inroads into any of the Jewish denominations. However, a small number of contemporary Jews choose to not circumcise their sons. They are assisted by a small number of Reform and Reconstructionist rabbis, and have developed a welcoming ceremony that they call the Brit shalom ("Covenant [of] Peace") for such children. [8] This ceremony is not officially approved of by the Reform or Reconstructionist rabbinical organizations. Rabbis in these movements strongly recommend circumcision for all male infants, and for all men who convert into Judaism. In contrast with Orthodox Judaism and Conservative Judaism, these liberal denominations, consistent with their view that traditional ritual law imposes no obligations binding on modernity, have generally made this a (strong) "recommendation" as opposed to an "obligation" (or "requirement"). Reform and Reconstructionist Judaism have often accepted medical circumcisions performed by doctors as sufficient to fulfill the commandment of brit milah. However, in recent years these movements have begun stressing the religious and ritual nature of circumcision and have begun training their own experts (mohalim) in this ritual.
  
  The anti-circumcision movement
  
  Circumcision in the Bible
  Zeved habat (welcoming ceremony for girls)
  Redemption of First-born (Pidyon ha-ben)
  Brit shalom
  Vacht Nacht (Ceremony the night before the Brit Milah)
  Shalom zachar Festive Meal on the first Friday night after the birth of a boy. Sources That Favor Brit Milah
  
  Jewish Circumcision.org - An anti-circumcision site that advocates for Jews to abandon the Brit Milah.
  Noharmm.org - An anti-circumcision article from a "Jewish feminist" perspective.
  City Risking Babies' Lives… - Controversy over metzitza be'peh.
  Af-Mila - An Israeli anti-circumcision organization.
  Jews Against Circumcision - A group of Jews that advocates for Brit Shalom.