PERIOD OF WAITING
The period of waiting is called Iddah(العدة) in period, it is the waiting period of a woman which she should observe when she is either divorced or widowed.
Types of Iddah
- Iddah of a divorced woman
- Iddah of a Widowed woman
Iddah of a Divorced Woman
“Divorced women remain in waiting, [i.e, do not remarry] for three periods”. Surah Al Baqarah 2:228
“And those who no longer expect menstruation among your women, if you doubt , then their period is three months [also for] those who have not menstruated. And for those who are pregnant, their term is until they give birth. Surah Al Talaq 65: 4
2. If not consummated
If the woman is divorced by talaaq before the man has entered upon her and been alone with her, i.e., before intercourse or intimacy with her, then she does not have to observe any ‘iddah at all. Simply by virtue of the divorce it becomes permissible for her to marry another man. 
3. If Pregnant
If she is pregnant then her ‘iddah lasts until the pregnancy ends and she delivers, whether that is a long time or a short one. It may so happen that he divorces her in the morning and she gives birth at noon, in which case her ‘iddah is over. Or it may be that he divorces her in Muharram and she does not give birth until Dhu’l-Hijjah, so she remains in ‘iddah for twelve months. The point is that the ‘iddah of the pregnant woman lasts until she gives birth, no matter what the case, because Allaah says (interpretation of the meaning):
“And for those who are pregnant (whether they are divorced or their husbands are dead), their ‘Iddah (prescribed period) is until they lay down their burden” Al-Talaaq 65:4 
4. If Not Pregnant
- If Menstruates
If the woman is not pregnant and she menstruates (is of child-bearing age), then her ‘iddah is three complete menstrual cycles after the divorce, i.e., her period comes then she becomes pure, then her period comes again and she becomes pure, then her period comes again and she becomes pure. That is three complete menstrual cycles, regardless of whether the time between them is long or short. Based on this, if he divorces her and she is breastfeeding and does not menstruate until two years later, then she remains in ‘iddah until she has had three menstrual cycles, so she may stay in this state for two years or more.
The point is that she should go through three complete menstrual cycles whether the time involved is long or short, because Allaah says (interpretation of the meaning): “And divorced women shall wait (as regards their marriage) for three menstrual periods” al-Baqarah 2:228 
- If she does not menstruate
If a woman does not menstruate, either because she is very young or old and past menopause, then her ‘iddah is three months, because Allaah says (interpretation of the meaning):“And those of your women as have passed the age of monthly courses, for them the ‘Iddah (prescribed period), if you have doubt (about their periods), is three months; and for those who have no courses [(i.e. they are still immature) their ‘Iddah (prescribed period) is three months likewise…”Al-Talaaq 65:4
- Other Situations
- If a woman’s periods have ceased for a known reason and she will not menstruate again, such as if her uterus has been removed (hysterectomy), then she is like one who has passed menopause and her ‘iddah is three months.
- If her periods have ceased and she knows the cause, she should wait for the cause to cease and for her periods to return, then she should observe ‘iddah according to her menstrual cycle.
- If her periods have ceased and she does not know what caused that, then the scholars say that she should observe an ‘iddah of a full year, nine months for pregnancy and three months for ‘iddah. 
Iddah of a Widow
And those who are taken in death among you and leave wives behind - they, [the wives, shall] wait four months and ten [days]. And when they have fulfilled their term, then there is no blame upon you for what they do with themselves in an acceptable manner. And Allah is [fully] Acquainted with what you do. Al Baqarah 2:234
2. Time Period
The ‘iddah of a woman whose husband has died is four months and ten days, because Allaah says (interpretation of the meaning):“And those of you who die and leave wives behind them, they (the wives) shall wait (as regards their marriage) for four months and ten days” Al-Baqarah 2:234
This period begins when the husband dies, and ends when the time is over, whether the wife adheres to the rulings on mourning or not, and whether she knows of her husband’s death or not. When four months and ten days have passed from the time of his death, then her ‘iddah ends
The ‘iddah for one whose husband dies is four months and ten days immediately following the death, and until giving birth if she is pregnant.
The basic principle is that a woman should mourn in the house of her husband where he died, and she should not go out except in cases of need or necessity, such as going to the hospital if she falls sick or buying what she needs from the marketplace such as bread and the like, if she does not have anyone who can do that. 
3. Conduct of a Widow
The widow who is observing her `iddah - the waiting period following the death of her husband – is required to adhere to some special conditions.
She has to stay in the house that was her residence at the time that her husband died until the end of her `iddah. The duration of the `iddah is four months and ten days, unless she is pregnant, in which case her `iddah will be until she gives birth.
She may not go out of the house except for necessities such as going to the hospital due to illness or in order to purchase what she needs from the marketplace, like food, if there is no one available to make those purchases for her.
- In case something happens to the house itself, she may go to live elsewhere. She may also leave her house if she has no one to keep her company and she fears for herself. In such situations, she may go to another house in consideration of her needs.
- The woman while observing `iddah may not wear beautiful clothes. It makes no difference whether those clothes are yellow, green, or any other color. She must wear clothes that are not beautiful, regardless of whether those clothes are black, green, or some other color. What matters is that the clothes are not beautiful, because this is what the Prophet ﷺcommanded.
- Also, the woman may not wear jewelry like gold, silver, pearls, and diamonds in any form, including rings, chains bracelets, and armlets.
- She may not wear perfume of any type. However, she may use incense only on the occasion of attaining purity from her menses. She may not use henna, saffron or perfume. She may not use saffron in her clothes or for her coffee, as it is a type of perfume.
- Also, she should avoid using antimony in her eyes or applying any type of cosmetics to her face. She may apply nothing to her face that might beautify it in a provocative way, though normal beauty care with the use of soap and water is permitted. However, antimony that beautifies the eyes and all other kinds of cosmetics must be strictly avoided.
- With respect to the notions that some common people have concocted – that the woman in `iddah may not talk to anyone or use the telephone, or wash except once a week, or that she may not walk in her house barefoot or under the moonlight, and other similar fictions – they are all quite baseless.
- She may walk around in her house with or without her shoes, do her own things in her house, cook food for herself and her guests, walk under the moonlight on the roof of the house or in the garden of her house, wash whenever she likes, talk to whomever she wants in a reasonable, modest manner, and shake hands with woman and her close male relatives (but not with non-mahram men). She may remove her head covering when there are no strangers present.
- The woman in `iddah may not be approached by anyone for marriage. Talk of marriage may be hinted at indirectly, but no direct proposals are allowed. 
Sa`id bin Musayyib and Abu Al-`Aliyah stated that the wisdom behind making the `Iddah of the widow four months and ten nights is that the womb might contain a fetus. When the woman waits for this period, it will become evident if she is pregnant.
Similarly, there is a Hadith in the Two Sahihs narrated by Ibn Mas`ud stating: ((The creation of) a human being is put together in the womb of his mother in forty days in the form of a seed, and next he becomes a clot of thick blood for a similar period, and next a morsel of flesh for a similar period. Then, Allah sends an angel who is ordered to breathe life unto the fetus). Sahih al-Bukhari 3208
So, these are four months and ten more days to be sure, as some months are less (than thirty days), and the fetus will then start to show signs of life after the soul has been breathed into it. 
Another reason is to raise the esteem of marriage, honor its status, and show its reverence.
`Iddah also aims at lengthening the period of revoking a divorcee, so that the husband might feel regret and take back his wife. Another reason is to give the husband his due right and show the consequences of losing him by preventing the wife from beautifying herself. That is why it is prescribed for women to mourn over their husbands more than they do over their parents or children.
Also, `Iddah is prescribed as a way of respecting the husband's right, the wife's interest, the children's right, as well as fulfilling the right of Allah which He has ordained. Thus, `Iddah involves four rights. Since marriage ends with the death of one of the spouses, the Law-Giver (Allah) has made death similar to the consummation of marriage in the consequences pertaining to Mahr (mandatory gift to a bride from her groom) and the prohibition of marrying one's stepdaughter, as in the opinion of a group of Sahabah (Companions of the Prophet) and their followers, such as Zayd ibn Thabit and Ahmad in one of the two narrations ascribed to him.
Thus, the reason for `Iddah is not only to establish the absence of pregnancy, for this is only one of its reasons and wisdoms. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, ﷺ 
Women in Islam; Pregnancy; Menstruation; Mahram; Marriage in Islam; Treating Wife; Spousal relation in Islam;