The Niddah is the principal command of a whole of Jewish religious laws called taharat hamishpa' ha , i.e. laws of family purity .

The principle is that the married woman is regarded as ritually (and not morally or physically) impure for the period of her rules and that implies a temporary physical separation of the couple.

In practice, the couples which observe this command abstain from physical relations and with stronger reason sexual for the period from the rules. The Jewish women took on them to add at this period 7 days after the last trace of blood. The couples must also sleep separately for this period. At the end of the period, the woman must go to the Mikvé (ritual bath) to take again the marital rhythm of life.

“Niddah” is also the name of a treaty of the Talmud which is exclusively devoted to this subject. It takes for reference the text of the Torah and more precisely the verses of the Lévitique (15: 19-30, 18:19, 20:18). The complexity of the subject is such as the Jewish woman often consults rabbinical authorities on this subject. Also, of many Jewish women the principles of the niddah assimilated and give courses the young grooms.

This command is the subject of debates. Some (E) S regard it as antiquated or sexist. For others, it can have a positive direction for the women: religious attention range with the female body, sexual “meeting again” of the couple made more intense by separation. The majority of the liberals and the Jewish feminists renewed the ritual ones bound to mikvé.

Traditionally, the Rabbin S attach a great importance to it so much so that a Jewish community should make pass the construction of mikvé before any other priority.