This Halacha is an excerpt from our Sefer
One may not drink wine throughout the nine days.
Does the prohibition begin from sunset or Tzeis of Rosh Chodesh? Some are accustomed to avoid drinking wine starting from after sunset of Rosh Chodesh. Others are accustomed only from nightfall [Tzeis]. See Introduction for the full details of this matter!
Adding wine into the ingredients of a food: It is forbidden to eat a food which contains wine within its ingredients. If wine fell into a food the food may be eaten if it contains sixty times the wine. Alternatively, one may taste the pot to verify if it has a taste of wine. If one sees that it does not have a taste of wine it is permitted.
Children: A child that has not reached the age of Chinuch may drink wine during the nine days as explained in the previous Halacha B regarding meat. See there for all the details of this matter!
Shabbos: One may drink wine on Shabbos without limitation. If the third meal continues past the conclusion of Shabbos, it remains permitted to eat meat and drink wine until one recites Birchas Hamazon, even if the congregation already Davened Maariv. Some Poskim however rule it is forbidden to drink wine past nightfall if the congregation already Davened Maariv.
Seudas Mitzvah: One may drink wine by a Seudas Mitzvah, as explained in Halacha 8C.
Kos Shel Bracha: One does not say Birchas Hamazon over wine during the nine days.
Havdala: When saying Havdala during the nine days [Motzei Shabbos Chazon] one is to give the wine to drink to a child [whether male or female, although some rule only male] who has reached the age of Chinuch [of blessings although some say also Chinuch of Havdala] but has not yet reached the age of Chinuch for mourning. If such a child is not , he may drink the [entire] Havdala wine himself as usual.
May one drink grape juice during the nine days?
May one drink grape flavored soft drinks during the nine days?
Yes, so long as they do not contain actual grape juice in their ingredient.
If one forgot and said a blessing over wine during the nine days, what is he to do?
He is to eat and swallow a small amount of the wine.
 Second opinion in Michaber 551:9; M”A 551:26 “and so is the law by Rosh Chodesh according to us”; M”B 551:58 “So is the custom in these provinces” based on Derech Hachaim and Chayeh Adam; Kaf Hachaim 551:125-126
Other Customs: The Michaber ibid records three customs in abstaining from meat and wine: 1) From the week of Tisha B’av; 2) From Rosh Chodesh; 3) From the 17th of Tammuz. [ibid]
The reason: As meat and wine bring joy. Thus, although even an Avel may eat meat and drink wine, by the Aveilus of the Temple we are more stringent. [Mateh Yehuda 551; Kaf Hachaim 551:119]
 M”A 551:36
 So rule regarding meat and the same applies for wine: M”A 551:29; Beir Heiytiv 551:29; Mishneh Berurah 551:63
Other Opinions: Some Poskim rule one may eat a Tavshil Shel Basar. [Kol Bo; Yeish Mi Sheomer in Michaber 551:10; Taz 551:9 and 11 rules one may eat gravy of a meat stew, as well as a dish which contains wine, even if one can taste it. Teshuvos Vehanhagos 2:259 rules one may add wine to pastries and the like even if one tastes the taste of wine in the food. [See Piskeiy Teshuvos 551:39]
 Some rule one may even do so initially if there is 60x the wine or its taste is not felt. [Piskeiy Teshuvos 551:39 in name of Sheivet Hakehasiy]
 Peri Megadim 551 A”A 29; Mishneh Berurah ibid; Kaf Hachaim 551:142
 P”M ibid; Shaareiy Tziyon 551:68
 Shaareiy Teshuvah 551:11
 Rama 551:11
 Rama 551:9; Maharil; See M”A 551:37; Taz 551:9 for explanation
 Rama 551:9 “One may slaughter meat for Shabbos”
 Elya Raba 551:23; P”M 551 A”A 26; M”B 551:56 based on Elya Raba and Derech Hachaim
 M”A 551:26
 Rama 551:10; M”A 551:32 in name of Mahril; Beir Heiytiv 551:31; Aruch Hashulchan 551:26; M”B 551:71; Yifei Laleiv 551:7 and Kaf Hachaim 551:152 that even Sephardim who are accustomed to drink the Havdala wine themselves [see next] do not drink wine for Birchas Hamazon as rules the Rama.
Other opinions: Some Poskim rule it is permitted to drink wine of Kos Shel Bracha for Birchas Hamazon. [Michaber 551:10]
 Rama 551:10
Other Opinions: Some Poskim rule one is to drink the wine himself by Havdala and is not required to give it to a child. [Michaber 551:10] This is the Sefaradi custom. [Kaf Hachaim 551:152] And so is followed even by some Ashkenazim. [Leket Yosher p. 210 that so did Terumos Hadeshen; Siddur Yaavetz; Darkei Chaim Veshalom 668] Some Poskim rule one is not to say Havdala over wine but rather over beer although some are accustomed to drink wine. [Aruch Hashulchan 551:26] See Hiskashrus on the nine days for a story recorded of the Rebbe that he told the person saying Havdala to give the wine to a child who was 11 years old.
 Based on 190:4
 Based on 295:4 that only one who fulfills their Havdala obligation may drink the wine, and women and girls are disputed in whether they are obligated in Havdala.
 Based on 190:4
 Kitzur Halachos 295 footnote 5 based on 295:4 that only one who fulfills their Havdala obligation may drink the wine. Vetzaruch Iyun Gadol on their ruling.
 M”A 551:31; Ashel Avraham Butchach 551; This means the child is not yet old enough to understand the mourning period.
Other opinions: Some write the custom is to give it to any child below Bar Mitzvah. [Orchos Rabbeinu; Piskeiy Teshuvos 551:35]
 Even if it is more than a Revius. [Piskeiy Teshuvos 551:35]
 Rama ibid
 Piskeiy Teshuvos 551:42 based on M”B 551:66; See Michaber 551:10 that one cannot drink Yayin Toseis, which is unfermented wine, which is similar to grape juice.
 Piskeiy Teshuvos 551:42
 Sdei Chemed ¼; Piskeiy Teshuvos 551:40