Judaism contains an ever-evolving set of traditions and customs. One of the more ancient and yet modern traditions is that of the mikveh. We find the first mention of mikveh in the Tanaach. “Only a spring, cistern, or collection (mikveh) of waters shall be cleansing” (Lev. 11:36). In this particular passage, mikveh has to do with the issue of when a person becomes ritually impure by coming into contact with unclean animals or foodstuffs. In order to become ritually pure again, the Israelites are to use the water from this mikveh in order to purify themselves.
An Israelite could become ritually impure for a variety of reasons. Whether it was because of childbirth, menstruation, coming into contact with the dead, or coming into contact with certain bodily fluids, the ritual immersion of a person in a body of water would serve as the means for their return ritual purity. Ritual purity in the Biblical context had to do with certain worship and communal rites. Some recent theories argue that mikveh was more about hygiene than ritual, which is an argument sometimes also made about Kashrut. However, the mikveh was always designed as a way to help the Israelites to achieve a level of holiness, when certain everyday acts, might distance them from God.
Since the destruction of the Second Temple in the year 70 CE, the mikveh has served as the means for those converting to Judaism. Brides and grooms also go to the mikveh, as well as families who are seeking to purify certain cooking and eating utensils.
However the mikveh is most commonly associated with niddah (family purity) since a wife, traditionally speaking, goes to the mikveh after her menstrual period before engaging in conjugal relations with her spouse. Because of this, the mikveh is most often associated with women in the Jewish community.
That being said, in a more modern context, the mikveh serves as a means for Jews, and those becoming Jews, to wipe their slate spiritually clean before beginning in a new endeavor such as conversion or marriage. The mikveh to us moderns is no longer just about niddah, it can serve us as a physical transformative element in our own lives, for any number of changes we might be going through.