Probationary period ('Iddat) is the compulsory waiting period for a woman after she is divorced or on the death of her husband. (Ghayatul Autar)
The probationary period ('Iddat) commences immediately after the death of the husband or divorce or cancellation of marriage and exhausts after the fixed period although the woman is unaware of the death or divorce. Because probationary period (Iddat) is the fixed duration and its knowledge is not the condition. (Ghayatul Autar)
The probationary period of a free woman if her husband had expired, is four months and ten days. (Ghayatul Autar)
Allah says:-
(S2-A234) And those who die
amongst you and leave widows behind, they shall wait
concerning themselves for a period of four months ten days. (Ghayatul Autar)
A free woman who is given divorce after sexual intercourse (whether Rajai or Bayan) or on cancellation of marriage, if she is having monthly course the probationary period will be three periods if not 3 months. But if divorce is given during the menses period that course will not be counted (Ghayatul Autar)
Allah says:-
(S2-A228) "The divorced women shall wait concerning themselves till three
monthly courses
(menses).
If an 'Aaisa is (woman who has menopause) divorced by her husband she should observe three months as probationary period, if after a month or so the menses starts, then the period is to be counted from that menses. Likewise if woman having menses is divorced and after one or two courses becomes dry (Aaisa), then the period of probation will be counted 3 months from the last menses. The period of TAHAR (menses) or the dry period passed will not be counted. (Ghayatul Autar)
The probationary period (Iddat) for a pregnant woman is up to the delivery.
Allah says:-
(S65-A4) "The women who are pregnant the probationay (iddat) period is that they
deliver (the child)"
A woman under probationary period (Iddat) should not adorn herself with ornaments etc. She should not wear saffron coloured clothes but coloured cotton clothes. She should not use scented oil and not apply henna and antimony for beauty. But it is permissible to use the things as a medicine to relieve pain. (Noorul Hadaya)
When probationary period (Iddat) becomes essential for a woman she should pass the probationary period in the same house in which they are separated or where the husband died or divorced.
Allah says:-
"Do not send them out of the houses, nor they leave the houses unless
some prostitute is brought in the house.
But when turned out of the house or there is a fear of loss of property or collapsing of house or house rent is not paid; in such conditions the wife has the right to leave the house. (Noorul Hadaya)
If the wife is passing the period of probation of revokable divorce (Tallaq-e-Bayan) then it is necessary that there should be purdah in the house. If the house is small then it is preferable that the husband should leave the house. It is also permissible that the wife leaves this house. Similarly if the husband is a sinner (Fasiq) then the wife may leave the house. But in any case it is preferable that the husband leaves the house.