"Mikvah" - (f., pl. "Mikvaot"); a ritual pool of water, used for the purpose of attaining ritual purity. Immersion in a Mikvah is performed for the following main purposes: It is used in connection with Repentance, to remove the impurity of sin. It is also used in connection with Conversion, because the convert has taken upon himself or herself to adopt the lifestyle of the Jew, that is based on the recognition of G-d as King of the Universe and on the obligation to perform the commandments of the Torah. It is the ritual act that divides two periods of time - the period of separation when marital relations are forbidden, because the wife is in the state of "niddah," and the period of union when such relations are not only permissible but regarded as essential to a healthy marriage. (See also "Taharat HaMishpacha" - family purity)
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B'Shem Y'shua