Etymology of the Hebrew and Aramaic term 
The noun mohel (mohela in Aramaic) "circumciser", is derived from the same verb stem as milah "circumcision." The noun appeared for the first time in the fourth century as the title of a circumciser (Shabbat 156a).
Origins of circumcision 
For Jews, circumcision is mandatory, as it is prescribed in the Torah:
- In the Book of Genesis as a mark of the Covenant between God and the descendants of Abraham: "Throughout all generations, every male shall be circumcised when he is eight days old...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"
- In Leviticus: "God spoke to Moses, telling him to speak to the Israelites: When a woman conceives and gives birth to a boy ... on the eighth day, the flesh of his foreskin shall be circumcised."
Biblically, the infant's father (avi haben) is commanded to perform the circumcision himself. However, as most fathers are not comfortable or do not have the training, they designate a mohel. The mohel is specially trained in circumcision and the rituals surrounding the procedure. Many mohelim are doctors or rabbis (and some are both) or cantors and are required to receive appropriate training both from the religious and medical fields.
Traditionally, the mohel uses a knife to circumcise the newborn. Today, doctors and some non-Orthodox mohalim use a perforating clamp before they cut the skin. The clamp makes it easier to be precise and shortens recovery time. Orthodox mohalim have rejected perforating clamps, arguing that by crushing and killing the skin it causes a great amount of unnecessary pain to the newborn, cuts off the blood flow completely, which according to Jewish law is dangerous to the child and strictly forbidden, and also renders the orlah (foreskin) as cut prior to the proper ritual cut.
Under Jewish law, a mohel must draw blood from the circumcision wound. Most mohels do it by hand with a suction device, but some Orthodox groups use their mouth to draw blood after cutting the foreskin.
Women as mohels 
All types of Judaism except for Orthodox Judaism allow female mohels, called mohelot (pl. of mohelet, f. of mohel). As the Jewish News Weekly of Northern California states, "...there is no halachic proscription against female mohels, [but] none exist in the Orthodox [Jewish] world, where the preference is that the task be undertaken by a Jewish man."
- Simeon J. Maslin, Central Conference of American Rabbis. Committee on Reform Jewish Practice Gates of Mitzvah: A Guide to the Jewish Life Cycle 1979 Page 70 "The term mohel (ritual circumciser) is derived from milah (circumcision). "
- Abraham P. Bloch The Biblical and historical background of Jewish customs- 1980 -p10 "Beginning with the fourth century, the term mohel (mohela in Aramaic) appeared for the first time as the title of a circumciser (Shabbat 156a). "
- Genesis 17:9-14
- Leviticus 12:1-3
- Rabbi probed for circumcised infants' herpes
- Making the cut