We are discouraged from doing dangerous activities during the Three Weeks before and including Tish'a b'Av.  But since it is forbidden to do dangerous activities anyway, there are few relevant activities that are forbidden. Some people do not travel during this time but it is not forbidden to do so. Non-urgent surgery should be scheduled for after this period.

Activities for socializing are not prohibited during the Three Weeks before Rosh Chodesh Av (but the activities might be prohibited for other reasons such as if they are dangerous).

If you are swimming for:

• Pleasure, you may swim during the Three Weeks but not during the Nine Days.
• Exercise (you don't particularly enjoy swimming or you are not doing it for fun or to cool off), you may be permitted to swim even during the Nine Days. Consult a rabbi.

You may move into a new home or apartment, whether owning or renting, during the Three Weeks before Tish'a b'Av. Ideally, you should not move into a new place during the Nine Days but if necessary, it is permitted.

Forbidden during the Three Weeks :

• Saying she'hecheyanu;
• Shaving;
• Haircuts;
• Listening to music (even recorded);
• Getting married.

Forbidden during the Three Weeks :

• Saying she'hecheyanu;
• Shaving;
• Haircuts;
• Listening to music (even recorded);
• Getting married.

For laws on swimming during the Nine Days, see Three Weeks: Swimming.

Restrictions during the Nine Days before Tish'a b'Av are the same as for Three Weeks, plus:

• You may not eat meat or drink wine.
  Exceptions

  1. You may drink wine on Shabbat (but not on Rosh Chodesh Av or erev Shabbat.)
  2. You may drink wine for havdala (but ideally give the wine or grape juice to a child between ages 6 and 10).  
  3. You may eat meat or drink wine at a brit, siyum, or pidyon ha'ben.
• You may not wear freshly laundered clothes, or wear or buy new clothes.

• You may not wash yourself for pleasure.
  Note Showering or bathing to clean one's soiled body is permitted (except on Tish'a b'Av).  So you may bathe or shower during the Nine Days if you are dirty, sweaty, or smelly.
• You may not do any activities that involve luxury.
• You may not say she'hecheyanu except on Shabbat.
  Note Therefore you should not buy new fruits or new items that you will enjoy during the Nine Days.  But if you DO eat a new fruit or buy something new, you must say she'hecheyanu anyway.

Before Tish'a b'Av we are in a type of mourning so the laws are similar to mourning for a parent. There are three stages:
The “Three Weeks”: The least severe stage starts three weeks preceding the Ninth of Av
The “Nine Days”:  The next-most severe stage begins on Rosh Chodesh Av.
“Week” of Tish'a b'Av:  The most severe mourning is during the “week” of Tish'a b'Av (beginning after Shabbat preceding Tish'a b'Av).

Introduction to Fast Days
The purpose of Jewish fast days is to make us reflect on our behavior and improve it by:

• Eliminating negative actions and thoughts, and
• Taking more care in our observance of the commandments.

God told the Jewish people on many occasions that He did not want their pointless sacrifices or fast days but rather wanted the Jews to improve their behavior. If people fast but still have reprehensible behavior, the people have missed the point and purpose of bringing sacrifices and having fast days.
All fast days may be circumvented for health reasons. Consult a rabbi.
Fast days come in several varieties:

• Major fast days: Yom Kippur and the Ninth of Av (Tish'a B'Av). 
• Minor fast days: There are four minor fast days; see below.
• Fast for First-Born
• Individual Fasts

The Major Fasts
Yom Kippur and the Ninth of Av begin before sunset and are both slightly longer than 24 hours. Yom Kippur is a festive day while, on the Ninth of Av, Jews mourn for the destruction of both Jerusalem Temples (the first was destroyed by Babylonians; the second, by the Romans). On both fasts, it is forbidden to:

• Eat or drink.
• Wear leather shoes (but you may wear any other clothing made of leather).
• Bathe (or even to wash anything more than fingers; you may not use a deodorant--not even a spray type--since it is similar to washing).
• Have marital relations.
• Use cosmetics or body scents.

The Minor Fasts
The four minor fasts begin 72 minutes before local sunrise. They technically end at dark but functionally end after ma'ariv (and for the Fast of Esther, after hearing the megila). Unlike most times in the Jewish calendar, this 72 minutes is normal time and NOT based on the current length of the day (sha'a zmanit):

• Fast of Esther (Ta'anit Esther): Day preceding Purim (or sometimes earlier).
• Fast of Gedalia (Tzom Gedalia): Usually the day after Rosh Hashana.
• Tenth of Tevet (Asara b' Tevet):
• Seventeenth of Tamuz (Shiv'asar b'Tamuz): Beginning of the Three Weeks of semi-mourning beforeTish'a b'Av.

On all fast days, eating and drinking are forbidden. The Tenth of Tevet and the Seventeenth of Tamuz additionally have the same restrictions as the Nine Days. So you may wash or bathe on the Fast of Esther and on Tzom Gedalia but not on the Tenth of Tevet and the Seventeenth of Tamuz. (See Nine Days: Restrictions).
Note On a fast day that has been delayed for Shabbat, there may be leniencies for:

• The mohel, sandak, and father of a baby getting a brit mila to eat after mincha.
• Pregnant or nursing women (this leniency applies to eating throughout the day).

Fast for First Born
Fast for first-born males 13 years old and older, on the day before Passover. This includes first-born cohanim and Levites (levi'im). The fast begins 72 normal minutes before sunrise and ends with kiddush at the seder. However, the widespread custom is to attend a siyum on the day before the first seder so that the first-born men do not need to fast on that day.
 
Personal Fasts
Fast by a groom and bride on their wedding day is an example of personal fasts. This fast begins 72 normal minutes before sunrise and ends with drinking wine under the chuppa.

You may eat tree fruit if the tree's buds appeared after Tu B'Shvat of the fourth year.  This may be a span of only 2.5 years if the tree was planted on or before Tu B'Av (at least 45 days before Rosh Hashana):

You may buy chametz food from a store owned by a Jew who owned chametz during Passover as long as two weeks or more have passed since Passover ended.

Although it is preferable to join a minyan whenever possible, prayer services may be said without a minyan. However, certain prayers may be said (or omitted) only with a minyan present:

• Bar'chu (morning and night),
• The word “Eloheinu” in the birkat ha'mazon introduction,
• Kaddish,
• Kedusha,
• Reader's repetition of the amida,
• Sheva brachot (the seven blessings) at a wedding,
• Sheva brachot during the week following the wedding,
• 13 midot in selichot,
• Torah reading if there will be aliyot, and
• Skipping the three introductory words for the shema.

Outside of Eretz Yisrael, you do not need to affix a mezuza (even without a blessing) to an apartment, house, or other accommodation that you rent for less than 30 days.
If you are living in a rented house, apartment, RV, etc., and remove all of your possessions used for living (such as clothing, bedding, and toiletries) at some time before 30 days have elapsed, the place is not considered to be your domicile. You restart counting the 30 days from the day you move the personal items back inside. 
Situation You rent a vehicle for 30 or more days but live and sleep there only five days a week (and remove all your personal items to spend Fridays and Shabbats with a family or in a hotel)
What to Do You will not be considered to be living there; you must affix a mezuza only if you leave some personal effects in the vehicle continuously for at least 30 days.

Only three of the Four Sons' questions are mentioned in the Torah (which all related to the Passover sacrifice), since the fourth (smallest) child cannot ask questions. Regarding this child, the hagada says, "Aht p'tach lo" (in the feminine).
Reason  The mother is supposed to be a child's primary teacher while the child is young.
There is a difference in attitude between the wise son and the evil son: The wise son says "Eloheinu" (OUR God); he is asking a question and seeking and answer. The evil son makes a statement (sort of a rhetorical question), instead of asking a question for which he seeks an answer. Yet, regardless of the sons' level of observance, it is a commandment to teach them about going out of Egypt.