The earliest time to remove tefilin on normal weekdays is after saying u'va l'tzion.

Only yashan grain should be used. Yashan means one of the Five Grains that was planted at least three days before Passover and has now passed the first day of chol ha'moed of Passover.  Grain planted after one Passover that has not passed the first day of chol ha'moed of the following Passover is known as “chadash.”

You may not do any types of expert or professional work after halachic midday before the first Passover seder.  These types of prohibited work are whatever would be prohibited on chol ha'moed.

You may put the myrtle and willow branches into water after using them only if they were in water before the Sukkot holiday began. You may not add water on Shabbat, but you may on the other Jewish festival days. You may change the water only on chol ha'moed.
 

Do not do any “work” while the Chanuka candles are burning.

Since two days of Jewish festival are observed outside of Eretz Yisrael, read the lines for the sacrifice for both days that might have been the correct day.

You may not waste people's time or upset them (tircha d'tzibura).

The dead person benefits if his/her son or sons lead public prayer services, whether during shloshim or the entire year (11 or 12 months). However, if the mourner is uncomfortable leading the minyan or is not a good reader or will be embarrassed, he should not feel obligated to do so.

 

A mourner does not lead a minyan on:

• Shabbat;

• Jewish Festivals (including chol ha'moed);

• Purim;

• Rosh Chodesh.

Opinions differ concerning Chanuka, so follow your local custom.

Here are the times when men and women are forbidden to get haircuts and men are forbidden to shave, including their necks (from most severe restrictions to least):
Most Severe Restrictions

• Mourner for parents (no shaving for the first 30 days and no haircut until three months after his or her previous haircut).
  Note If mourning for other relatives, you may get a haircut after 30 days.
• From Saturday night before Tish'a B'Av until the evening after Tish'a B'Av.
• Chol ha'moed.

Next Most-Severe Restrictions
Shiv'asar B'Tamuz (17^th of Tamuz) until the evening after the Shabbat preceding Tish'a B'Av.

Least-Severe Restrictions
During 33 of the 49 days of counting the omer (sefirat ha'omer); that is, either from the second day of Passover until Lag Ba'Omer (33rd day of the omer) OR from Rosh Chodesh Iyar until the day before Shavuot, according to your custom.

You must tear four vertical inches at the neck of your shirt (and jacket, too, if you wear one) when seeing the ruins of the Temple in Jerusalem for the first time in more than 30 days. You do not need to be close by; do kri'a even if you see the mosques that are on top of the Temple mount.

Jewish Festivals are listed in the Torah and are of two types: 

1. Three pilgrimage festivals (shalosh regalim):

• Passover,
• Shavuot, and
• Sukkot (including Shimini Atzeret).

These festivals were celebrated in ancient times by "appearing before God"--by bringing offerings to the Tabernacle or Temple.

2. High Holidays: 

• The Jewish New Year (Rosh Hashana—“Yom Teru'a” in the Torah), and the
• Day of Atonement (Yom Kippur).

 
Duration
Jewish holidays that were originally one day are now observed as follows:

• Rosh Hashana--2 days.
• Yom Kippur--1 day.
• Shavuot--1 day in Eretz Yisrael or 2 days elsewhere.
• Passover has festival days at the beginning and end of the holiday and intermediary days of lesser holiness, which are called chol ha'moed. In Eretz Yisrael, Passover lasts for 7 days in total and the first and last days are festival days. Outside of Eretz Yisrael, Passover lasts 8 days and has two festival days at the beginning and two at the end.
• Sukkot has festival days at the beginning and at the end and intermediary days of lesser holiness, which are called chol ha'moed. In Eretz Yisrael, Sukkot lasts for 8 days and the first and last days are festival days (the last day is Shimini Atzeret). Outside of Eretz Yisrael, Sukkot lasts for 9 days and the first two days and last days are festival days (the 8th day is Shimini Atzeret and the 9th day is Simchat Torah).

Character
Each holiday contributes its own character to Jewish life (Passover--the theme of freedom; Yom Kippur brings atonement, etc.). 

Celebrating
How to celebrate these holidays is detailed in our Oral Law and halacha books. Jewish festivals as practiced today are similar in holiness to Shabbat. As with Shabbat, the Jewish festival has candle lighting, kiddush at two meals, and havdala.   We eat our best food and wear our best clothing on Jewish festivals (we eat our next-best food and wear our next-best clothing on Shabbat!).
The main idea behind eating meals on Jewish festivals is joy (simcha), so you should drink wine and eat meat (only if you enjoy wine and meat).  There is no third meal on Jewish festivals since people used to eat two meals each day (adding a third meal on Shabbat was for enjoyment/oneg).
 
Melachot
Any activities or actions permitted on Shabbat are also permitted on the Jewish festivals. Actions that are forbidden on Shabbat are generally also forbidden on Jewish festivals, but there are some leniencies (only if the actions are needed for that festival day).
Examples

• Lighting from an existing flame,
• Cooking and baking for the Jewish festival day, and
• Carrying outside the eruv (hotza'a--transferring objects between domains).

 
Grama
Grama (indirectly causing an action) is permitted on Jewish festivals (but not on Shabbat). For example, you may advance or delay a timer that will make a light go on or off in the future (the timer must already be plugged in and operating from before sunset of the festival day).
Note For an action to be considered indirect based on time, there must be at least 2.5 seconds after the first action is done before the resulting action begins to happen.

Psik Reisha Dla Neicha Lei
Psik reisha dla neicha lei is forbidden on Jewish festivals, just as it is on Shabbat.

D'oraita Restrictions
D'oraita restrictions apply world-wide to:

• First and seventh days of Passover,
• First and eighth days of Sukkot,
• First day of Shavuot,
• Yom Kippur,
• First day of Rosh Hashana.

Note The same restrictions apply to all other Jewish festival days but are rabbinical.
 
Women
In general, women are not required to perform the positive, time-dependent commandments. Women and girls are not required to eat any Jewish festival meals except the Passover seder meal (but they are not allowed to fast on those days).

Situation Kitniyot were cooked in a Passover utensil. 
Situation 1 The kitniyot's volume was less than 50\% of the volume of food cooked in that utensil. 
Status The food may be eaten and the utensil may be used on Passover (no need to kasher). 


Situation 2 The kitniyot's volume was more than 50\% of the volume of the food cooked in that utensil.
Status The food is not permitted to be eaten. 


Situation 2a The kitniyot's volume was more than 50\% of the volume of the food cooked in that utensil, and the total volume of the food cooked (kitniyot + non-kitniyot) was less than the normal volume of food which is cooked in that utensil.
Status The utensil may be used even without kashering, as long as you wait at least 24 hours after the utensil has been cleaned. 


Situation 2b The kitniyot's volume was more than 50\% of the volume of the utensil itself and more than 50\% of the normal volume of food cooked in it.
Status You may not eat the food (until after Passover) and must kasher the utensil after waiting 24 hours. 
NOTE You may only kasher a utensil on chol ha'moed but NOT on the festival days themselves. 

Non-Kli
You may not use a kli for sukka schach.

A kli is any item created with the intention of being used as a tool or utensil to make an activity easier.

Examples

• Bamboo if it had been used for any other purpose.

• Wooden ladder.

• Walking stick.

Non-Edible
A sukka's covering (schach) must consist of non-edible branches, leaves, or other materials of plant origin such as boards. You may use wooden boards (such as 2” x 4”s) to hold up schach, even though lumber is intended to be used for construction.
Size
Boards or tree trunks—whether used as schach or used to hold up schach--must be not more than 15 inches (38 cm) wide. A board--whether used as schach or used to hold up schach--more than 15 inches wide invalidates the area below it and you would have to sit under kosher schach in order to fulfill the mitzva. In the case of a board more than 15 inches wide: If the sukka has only three walls, the board may invalidate the sukka. Consult a rabbi.
Fresh
You may not use branches whose leaves will dry up in less than 8 days, intending to replace the branches with fresh ones during chol ha'moed; the custom is to use evergreen leaves only if you want to use leaves as schach.
Fasteners
Schach on the sukka must stay by itself without fasteners or connectors, even in a place with normally high wind. Any man-made fasteners--such as plastic, metal, or even hemp cord or rope--will invalidate the schach. If the schach will stay without them, then you may use fasteners or connectors as reinforcements.

Year-Round Structures
You may use a pergola, gazebo, or other type of awning frame or roof structure that exists year-round for a sukka as long as the other conditions (size, slope, materials, timing, etc.) are kosher. You must first remove any permanent roof coverings before putting on the schach.

Note The slope of the sukka roof must be less than 45 degrees from horizontal.

Food Nullification in Utensils: Torah-Law and Rabbinic Decree
By Torah law (d'oraita), any clean utensil, countertop, etc., automatically reverts to neutral/pareve and kosher after not being heated to more than 120° F (49° C) for 24 hours.
But by rabbinic decree, utensils do not automatically become neutral/pareve even after 24 hours and must be kashered by heat (libun—direct heat; hag'ala—boiling in a pot; or eruy rotchim—pouring boiling water over item) or, if some types of glass, by soaking in water (meluy v'eruy ).
 
Changing Gender of Utensil
You may kasher a pot or cooking/eating utensil from:

• Non-kosher to kosher, or
• Year-round use (chametz) to kosher for Passover.

 
You may not intentionally kasher a utensil in order to change it from dairy to meat or meat to dairy; you must first kasher it from accidentally (or intentionally) non-kosher to kosher/pareve, or from non-Passover to Passover/pareve. You may then use it for either dairy or meat.

Once you have used it for that gender, the item retains that gender (unless you re-kasher it for Passover or you make it non-kosher first, then kasher it to neutral/pareve).
But if you accidentally heat meat with a dairy utensil or vice versa, you may kasher it back to its original gender by any one of the kashering methods, depending on how it became non-kosher.
 
Items/Materials that Can Be Kashered
The following materials can be kashered:

• Glass, including Corelle, if not used directly on the stove or oven. Glass does not change gender or other kosher status unless heated on a flame or in the oven. Unless it is heated in this way, glass does not ever need to be kashered (except for Passover) (see Meluy v'Eruy, below).Glass, including Corelle, if not used directly on the stove or oven. Glass does not change gender or other kosher status unless heated on a flame or in the oven. Unless it is heated in this way, glass does not ever need to be kashered (except for Passover) (see Meluy v'Eruy, below).Glass, including Corelle, if not used directly on the stove or oven. Glass does not change gender or other kosher status unless heated on a flame or in the oven. Unless it is heated in this way, glass does not ever need to be kashered (except for Passover) (see Meluy v'Eruy, below).

• Granite (not granite composite)
• Marble
• Wood, if smooth (see notes on Eruy Rotchim, below)
• Metal, including stainless steel, cast iron, and aluminum.

Note While metal can be kashered if thoroughly cleaned, welded handles and other difficult-to-clean parts may render a metal utensil not kasherable. You might be able to use libun kal on the problematic area and still use hag'ala for the remainder of the utensil.
 
Items/Materials that Cannot Be Kashered

• China
• Corian
• Corningware
• Crockpot
• Formica
• Glass that has been used directly (kli rishon) on a stove or in an oven; however it can be kashered in a kiln
• Granite (composite)
• Knives with Plastic Handles (knives with wooden handles may be kashered if there are no cracks in the wood and if the rivets do not have spaces that catch food and prevent you from cleaning it completely)
• Mixer-there might be exceptions. Consult a rabbi.
• Plastic
• Porcelain (Enamel)
• Pyrex (if used directly on stove or in oven--kli rishon)
• Rubber (synthetic)
• Silestone
• Silverstone
• Stoneware
• Teflon
• Toaster/Toaster Oven
• Waffle Iron.

 
Pot Lid Handle
Kashering
The handle on a pot lid does not need to be kashered for normal use during the year. 
Reason It does not normally get hot.
Cleaning
However, the pot lid handle must be removed and the lid cleaned where the handle attaches, if possible.
Note If the gap between the handle and lid cannot be completely cleaned, you may not use that lid for Passover and you normally may not kasher it if it becomes non-kosher. If the lid handle cannot be removed, consult a rabbi.

Pot or Pan Handle
A plastic handle that gets hot, especially if it is over a flame on a burner, may not be kashered. If the handle becomes non-kosher, it must be replaced. If a plastic handle connects directly to the metal of the utensil, consult a rabbi about what to do.
 
Food Nullification: Heat-Kashering
Three Methods of Heat-Kashering
Heat-Kashering is of three types:  Libun, Hag'ala, and Eruy Rotchim.

1. Libun (Direct Heat)
   How It Works  Burns up any residual food taste

       

• Direct a flame, such as a blowtorch, onto the inside of a pot. Pot is hot enough when a piece of paper that touches the outside of the utensil burns (it does not need to burst into flame, just to smolder), or
• Put the pot into the oven at 500 ° F for 40 minutes. (First, remove any non-metal handles; they will need to be kashered separately or not used.)

   

2. Hag'ala (Boiling)
    

• Boil Method Boiling water within the pot to be kashered, and making the boiling water overflow, or
• Dip Method Dipping a smaller pot or utensil to be kashered into a larger pot of boiling water.

       

• If the pot in which you are kashering the items had been heated to 120° F (49° C), with food of that gender in the pot, or more within the previous 24 hours, the items you are kashering will assume the gender of the pot.
• If the pot in which you are kashering the items had NOT been heated to 120° F or more for at least 24 hours, any items that are kashered in it will become kosher and pareve.

     
 

3. Eruy Rotchim (Hot-Water Pour)

         

 
Food Nullification: Meluy V'Eruy
Meluy V'Eruy To Kasher Glass
Halachically, “glass” includes Arcoroc, Corelle, crystal, Duralex, and Pyrex.
NOTE In pre-war Europe, where glass was expensive and hard to obtain, it was customary to kasher drinking glasses, especially for Passover, by soaking the glasses for three 24-hour periods (meluy v'eruy), as follows:
Step 1: Submerge glasses in cold water for 24 hours.
Step 2: Empty water, refill, and submerge glasses again.
Step 3: Repeat Step 2.
NOTE If any of these materials were heated directly on a flame or other heat source, they cannot be kashered by meluy v'eruy!