The Nine Days in Halakha:
Construction and decorations: Construction and significant decorating of one’s home are prohibited, unless one will suffer a substantial financial loss as a result. All critical repairs are allowed. Decorative planting is also prohibited.
Wine and meat: Meat (including chicken) is prohibited except on Shabbat or at a mitzvah meal (e.g., brit milah, pidyon haben or siyum). Pareve dishes cooked in a utensil used for meat are permitted. All wines and grape juices are prohibited. Food dishes cooked with wine are permitted. Beer, whiskey and wine-vinegar are permitted. The restrictions on meat & wine do not apply to a child, pregnant or nursing woman, or an elderly, sick or weak person who cannot eat dairy foods or who needs to eat meat for health reasons. Havdalah is recited over wine or grape juice, which an adult may drink, although some authorities prefer that grape juice be given to a child between the age or six and eight. Others have the custom to use beer for this havdalah.
Laundry: Laundering clothing, linen, towels and tablecloths is prohibited (even by a Gentile), except (1) for children whose clothing is often soiled, and (2) in the event that all of one’s clothing, linens, towels or tablecloths, as the case may be,are soiled (in which case, laundering is allowed for the minimum clothing, linens, towel or tablecloths required for the remainder of the “nine days”). Tailoring clothing is prohibited (but patching or sewing a rip is allowed). One may not wear new clothing and one may not wear freshly laundered clothing (except undergarments). Laundered clothing that was worn prior to the “nine days” for a short time may be worn. The custom is to allow fresh clothing and linen on Shabbat Chazon. New clothing should not be purchased, even items not requiring she’hechiyanu (except shoes for Tisha B’Av or for children who run out of clothing). A shoe shine is permitted for Shabbat. A sheitel is treated as clothing for these purposes and, therefore, it may not be washed, cleaned or professionally set.
Bathing and nail cutting: Bathing and showering for pleasure are prohibited, but they are allowed for health reasons and for women preparing for the mikvah. A number of authorities are of the opinion that since nowadays we are accustomed to bathe more frequently, one may take a short shower in warm water, even with soap and shampoo, when one feels very uncomfortable. Many authorities prohibit swimming but are lenient for children because of the heat of the summer. There is a dispute in halakha regarding whether one may cut his nails; therefore, it is recommended that one refrain from cutting nails, except on erev Shabbat or in the case of a woman preparing for the mikvah.
Entertainment: It is proper for one to not attend amusement parks or sporting events.
Tisha B’Av in Halakha:
Erev Tisha B’Av: Most years after Mincha, one should eat a seudah hamafseket, the final meal before the fast. At this meal, one may not eat more than one cooked item. The custom is to sit on the floor and eat bread and a hard-boiled egg with ashes. Three adult males should not eat together to avoid having to recite birkat hamazon. The fast and and restrictions begin at sunset.
Basic prohibitions: Eating, drinking, washing, anointing, marital relations, wearing leather shoes or sneakers, regular Torah study (including daf yomi), sitting on a regular chair (until midday), greetings (one may respond to a greeting in a serious tone), giving gifts, and “time-consuming work” (such as going to one’s job) are forbidden.
Exceptions to the Prohibitions:
Eating and drinking are permitted for:
(1) a person who is sick or an old or weak person who may become ill if he does not eat or drink, even if his illness will not endanger his life (but a mere headache does not allow one to break the fast, and pregnant & nursing women must fast unless they are feeling ill)
(2) boys under 13 and girls under 12
(3) swallowing a bit of water along with a prescribed medication if the medication cannot be swallowed otherwise (although it is preferable to add something to the water to make it bitter)
Washing is permitted for:
(1) soiled parts of the body
(2) to rinse off any discharge (e.g., in the eye)
(3) upon awakening in the morning, one should wash three times on each hand, but only until the knuckles
(4) after bathroom use and/or after touching a part of the body that is normally covered – until the knuckles
(5) rinsing the mouth with water; using mouthwash and toothpaste are only allowed in cases of great discomfort or if there is a medical reason & in such instance, care must be taken not to swallow the water
(6) if one is preparing food for children
(7) medical reasons
(8) preparing for davening, but only until the knuckles
(9) washing dishes (after chatzot) if leaving them unwashed will attract bugs
(10)washing for bread, for those who may eat on Tisha B’Av
(11)washing a baby
(12)a bride, to wash her face up to 30 days after her wedding
Anointing is permitted for:
(1) medical needs (e.g., applying ointment to a skin rash)
(2) to remove a bad odor (e.g., deodorant and baby powder, but not perfume)
(3) a bride, up to 30 days after her wedding
Leather shoes are permitted for:
(1) a person who must walk a long distance over stones or mud and no other suitable footwear is available
(2) medical needs
(3) children who are under chinukh age
Torah study is permitted with respect to:
(1) the story of the destruction of Jerusalem, e.g., Eichah, parts of Jeremiah, Gittin 56-58, Sanhedring 104, Yerushalmi at the end of Taanit, Josephus
(2) Iyov with commentaries
(3) Laws of Tisha B’Av and mourning
(4) Some allow mussar
It is strongly recommended, based on halakhic custom, not to go to work preferably for the entire duration of Tisha B’Av or at the very least, until chatzot. In cases of irretrievable financial loss, however, work may be done even before chatzot.
Note that all of the Niddah restrictions apply during the night of Tisha B’Av, but during the day, only marital relations are forbidden.
Tallit and tefillin: One’s tallit gadol and tefillin are not worn at shacharit. One’s tallit katan is worn at shacharit, but without a brakha.
Motzaei Tisha B’Av: Generally, a number of restrictions continue until midday of the next day, including bathing, haircuts, washing clothes, meat and wine, music and she’hechiyanu.