Please try not to add natter or unnecessary information. This is not a treatise or lecture on Jewish Holidays; it is Useful Notes.
Maxwell: Now is this the holiday Miss Fine said you can't eat all day, then stuff yourself; or the one where you light candles, then stuff yourself; or the one where you build a straw hut, then stuff yourself?
Niles: I believe it's the one where you hide crackers from small children, then stuff yourself.
Most Jewish holidays, as the saying goes, can be described in nine words: "They tried to kill us. We won. Let's eat." With the exception of fasts, when it goes: "They tried to kill us. They managed it. Let's not eat."
Having said that, there are quite a few fast days as well. And because there's so much variety in Jewish practice, descriptions tend to vary. Unless otherwise stated, the practices described here correspond to Ashkenazi Orthodoxy, which can be seen as a sort of "template" for the others. Since All Jews Are Ashkenazi in popular media this is often a default mindset. Many Jews are less observant or non-observant and won't strictly follow, or even be aware of, all of these holidays; the ones they are most likely to observe would include Yom Kippur, Passover and Hanukkah.
A Jewish holiday is known as a yom tov (literally, "good day"). On any yom tov, one greets a fellow Jew with "gut yom tov" in Yiddish or "chag same'ach" in Hebrew.
There are three kinds of holidays:
- "Major Holidays": They originate from the Torah (Genesis, Exodus, Leviticus, Numbers and Deuteronomy), the first five books of the Judaeo-Christian religious canon. On these days, "work" is forbidden in mostly the same way it is on the Sabbath (cooking is allowed, as is transferring flame from one already-burning fuel source to another. Starting a new fire is not allowed). This includes operating electrical devices like light switches, riding buses, conducting business, and a myriad other laws. To confuse you further, this is known as a yom tov when compared against chol hamo'ed (below) — but the full holiday is also known as yom tov, so context matters.
- "Chol Hamo'ed" (literally, "Mundane Part of the Holiday"): On Passover, which is 7-8 days long, and Sukkot, which is 8-9 days long, only the first and last 1-2 days are full holidays. The ones in between are more or less minor, and many different kinds of "work" are permitted. Just how much is permitted depends on how lenient the observer is.
- "Minor Holidays": They originate from observances outside the Torah. Unlike the major holidays, work during these days is allowed.
- "Fast days": No work is forbidden on these, for the most part (except on Yom Kippur), but eating and drinking is forbidden. Unlike most holidays, the minor fast days start from sunrise, not sunset of the previous day (this incidentally makes their rules more or less identical to the fast in Islam). The major ones (Yom Kippur and Tisha B'Av) do start from sunset.
The Jewish CalendarThe Jewish calendar is lunisolar — that means it attempts to simultaneously follow the phases of the Moon and the seasons. Each of its 12 months are 29-30 days, each roughly following the duration between two consecutive New Moons. However, this results in a year of only 353-355 days (depending on the length of the months), 10-12 days shorter than the solar year. To make sure that the holidays fall in roughly the same time every solar year, an extra month is added on every so often (7 out of every 19 years). The month names (which was derived from the Babylonian calendar, a product of the Jews' long exile) are as follows:
- Marcheshvan/Heshvan (the only month that, for most denominations, has no holidays, hence the addition of "mar," which is Hebrew for "bitter")
- Adar Aleph (i.e. 1), the extra month
- Adar Bet (i.e. 2) (just Adar outside leap years)
Since months begin on the new moon, any given holiday is always on the same moon phase every year. For example, Passover always begins on a full moonnote .
The ecclesiastical year starts at Nisan, which roughly approximates the nearest New Moon to the Equinox of 21 March (thus Adar is placed at its very end), while the civil year starts at Tishri, which in turn approximates the nearest New Moon to the Equinox of 23 September, which marks the start of the Near Eastern agro-economic cycle.
By the way, if you've played Xenogears, you may recognize the month names or mistranslations of them.
Jewish years are termed "Anno Mundi" (AM), which begins on 1 Tishri, the afternoon of 6 September 3761 BCE, calculated by some Talmudic scholars to be the date when God created the world.
All days technically begin the sunset of the day prior, so on a "major holiday" (where "work" is forbidden, like using electrical devices or conducting business) the restrictions begin on sunset the day before and last until after dark on the next day.
In Israel, most of the "major holidays" are all only one day long. Outside of Israel, though, all major holidays are two days long. This is historical: back before telephones, the appearance of the new moon, which signals the beginning of a new month, was "announced" via messenger. To those places far outside Jerusalem, by the time the holiday was due to come around they still didn't know how long the previous month had been (29 or 30 days), and thus to be safe they kept both possible days.
Rosh Hashanah (Head of the Year) — 1-2 Tishri
One of the most important holidays in the calendar, marking the beginning of the civil year. It is also the exception that proves the rule: a holiday that is two days both in and out of Israel. Rosh Hashanah, together with Yom Kippur, are known as the yamim nora'im ("Days of Awe"), also known as the "High Holy Days". During this time, Jews are exhorted to examine and repent of their sins, as it is believed that on this day God starts judging humanity for their actions during the previous year and seals their fate for the whole year ten days later (Yom Kippur). Thus, "Happy New Year" is often deemed an inappropriate greeting; traditionally it has to be "l'shana tova tikatev v'techatem" ("may you be written and sealed for a good year"), or simply "shana tova" ("have a good year").
Prayers on Rosh Hashana are much more liturgical and much longer than during a normal holiday. Some of this is taken up by the shofar, a horn (usually that of a ram or greater kudu, a type of antelope) which is sounded a hundred times in order to "awaken" Jews to repent.
Food! Starting from here, the challah (a kind of braided bread) eaten every Shabbat are dipped in honey to symbolize the desire for a "sweet new year". Some communities also eat round/circular challah throughout Tishri. On the day itself it's common practice to dip an apple in the honey as well. It is also customary to eat the head of a fish (symbolizing the "head" of the new year). This may be substituted for gefilte fish, but then again many Ashkenazis will eat the fish at any festive opportunity. There are a great many other simanim ("signs") that various groups eat on this day, including the fish head (or, more commonly for Sephardim and Mizrahim, cow tongue) and honey. All of them have some kind of linguistic justification or pun associated with them as well as a short blessing, many of which refer to hopes of vanquishing their enemies.
Aseret Yemei Teshuva (Ten Days of Penance) — 1-10 TishriNot so much a holiday as it is a period of reflection and penance.
Tzom Gedalia (Fast of Gedaliah) — 3/4 TishriA fast observed from dawn to dusk, mourning the assassination of Gedaliah ben Ahikam, the governor of Judah appointed by King Nebuchadnezzar II of Babylon to administer to Jews left behind after the majority were exiled to Babylon, by some Jews opposed to his appointment in spite of his efforts to restore order following the destruction of the Temple, forcing the remnant to flee to Egypt for fear of retaliation and thus dashing any semblance of autonomy. The assassination is generally believed to have occurred on a Rosh Hashanah, thus out of respect the fast is moved to the third of Tishri, except if it is a Shabbat, in which case it is moved to the fourth.
Erev Yom Kippur (Eve of the Day of Atonement) — 9 TishriLiterally the day before the big day, this is marked by additional morning prayers, exchanges of forgiveness, giving to charity and two festive meals — think of it as the Mardi Gras of Jews.
Food! Plentiful, as a preparation for the day-long fast.
Yom Kippur (Day of Atonement) — 10 TishriYom Kippur itself is not only a "major holiday" but also a fast day. However, unlike most other fasts, not only food and drink are forbidden, but also makeup, leather shoes, hand washing and sexual relations (Tisha B'Av is the only other day with these restrictions). The entire day and much of the preceding night is spent in the synagogue praying for forgiveness and reconciliation with God before their fates are sealed for the year after a ten-day examination which began at Rosh Hashanah.
Food! None. Too bad.
Sukkot (Feast of Booths) — 15-21 Tishri (22 Tishri outside Israel)Occurs five days after Yom Kippur (yes, Tishri is a busy month). One of the big three holidays in the calendar and originally one of the three times when Jews are obliged to go to the Temple in Jerusalem (besides Passover and Shavuot). Sukkot is more of an agricultural festival, but nowadays is mainly known for the sometimes elaborate wooden huts that spring up in any heavily Jewish area. Jews eat and (some) sleep in them for seven days, celebrating God's providence throughout the Jews' journey out of Egypt, during which time they had to sleep in huts.
When in the synagogue, men will carry the Four Species: the etrog (a yellow citronnote ), the lulav (palm frond), the hadasim (myrtle branches) and the aravot (willow branches). The latter three are bound together in one bundle. During the prayers, the Species are held and waved around at various points. Historically, many congregations could not access some or all of the Species (this was a particular problem among Ashkenazis in Europe and, later, North America), so it was common for a synagogue to have only one of each, but today all the men having a full set is pretty common.
The last day is known as "Hoshana Rabbah". There are some aspects of the High Holy Days that trickle down here. The prayers are longer, and near the end, the men will take a bundle of five aravos and bash them against the ground several times. This is very symbolic and has nothing whatsoever to do with letting out the stress of building huts and cooking and cleaning so much.
Shemini Atzeret (Eighth Day of Assembly) — 22 TishriUsually observed outside Israel (where it is considered the eighth day of Sukkot), Shemini Atzeret is both an extension of Sukkot and the eve of Simchat Torah.
Simchat Torah (Rejoicing with the Torah) — 22 Tishri (Israel) / 23 Tishri (world)Simchat Torah is a day in which Jews celebrate the completion of the Torah reading for the year. They dance with Torah scrolls in the synagogue and often get blindingly drunk.
Food! Nothing in particular, just lots of it. The challah is still dipped in honey all the way up until Simchat Torah.
Sigd (Day of Worship) — 29 CheshvanThis relatively unknown holiday is nevertheless of very high importance to Ethiopian Jews, and is celebrated mostly by this community in Israel and among the Jews still living in Ethiopia. It takes place exactly 50 days after Yom Kippur.
Sigd, also known as Mahelela ("Praise"), celebrates a couple of important events mentioned in the Torah (primarily the events following the Great Flood and at Mt. Sinai) and is also a general re-affirmation of the Jewish faith and allegiance to God. As a supplement to Yom Kippur, fasting is also pretty common on Sigd, so it has no special foods.
Chanukah — 25 Kislev - 2 Tevet (3 Tevet, if that year Kislev has only 29 days in it)
Or Hanukah, or Channukkah, or for those truly addicted to spelling, Chhhannnukkkkahhhh.note The most well-known of the Jewish holidays, and ironically one of the least important in the calendar. Chanukah is the most recent holiday added to the universal Jewish calendar (around 100 BCE) and is classified as a "minor holiday" (i.e. work is permitted).
The story of Chanukah involves the Chashmona'im, a family of priests in power, and the Maccabees, a specific set of people in the family. The Syrian-Greeks, in occupying Israel, eventually started banning Jewish practices and even defiled the Jewish Temple. The Chashmona'im led a rebellion against them and ousted them from power. It is worth noting that this is the first recorded war for religious freedom. When they got back to the Temple, though, they couldn't find any unspoiled oil to light the menorah, a holy ceremonial candelabra. They finally found one jar of oil still sealed, but it was only enough for a single day. However, miraculously, the oil lasted eight days, leaving them enough time to manufacture new oil.
To commemmorate the war and the miracle, Jews light a chanukiyah, a smaller version of the menorah with a total of nine lights: one for each night, plus a shamash or "helper" light. The shamash is necessary because the lights themselves are forbidden to be used for their light. Each night, one more light is lit (so one plus shamash on the first day, two plus shamash on the second day, up to 8 + 1 on the last day).
By its nature, Chanukah is totally dissimilar from Christmas other than falling around the same time of year. We get annoyed when people try to conflate the two.
The iconic game played on Chanukah is the dreidel, a spinning top with four sides. On each side is a letter: "Nun", "Gimel", "Heh", "Shin", which spell an acronym for Nes Gadol Hayah Sham, "a great miracle happened there". In Israel, the Shin is replaced with a Peh, which changes the meaning to "a great miracle happened here". Money is put into a pot (like in poker) and depending on what side the dreidel comes down on, you either put in or take out. It should be noted, however, that because the only "move" a player can make is spinning the dreidel, it is actually really boring to play, and only children and people who don't know better will actually take it seriously. One couple tried mixing it with Texas-hold-'em, but we're getting off-topic now. Side note: Dreidel becomes quite a lot more fun when you make it a drinking game.
As a side note, in Israel it's also gotten a bit more important than is traditional or justified on purely religious grounds, though for completely different reasons: there, the whole fight-for-independence angle is played up, and depending on the political and social climate the importance of military strength may be emphasized. In a sense, it's become Israel's Armed Forces Day.note
Food! Fried foods are eaten on Chanukah (because they're made with oil). Popular ones are latkes or levivot (fried potato pancakes) and sufganiyot (jelly doughnuts—if you're from the American Midwest, think of paczkis, as there isn't any real difference). Mm, feel those arteries harden, and those digestive systems moan! Chocolate coins may be available for purchase as a type of Chanukah gelt.
For more details on (C)han(n)uk(k)ah, see this video.
Asara B'Tevet — 10 Tevet
A minor fast day from sunrise to sunset, this day commemorates the beginning of the siege of Jerusalem by Nebuchadnezzar.
Tu Bishvat — 15 Shvat
A very minor holiday, this marks the "new year for trees". (The name just means "15th of the month of Shvat"). Some people will eat extra dried fruits or nuts today, often having a rare fruit they haven't had all year so that they can recite a special blessing over it.
In Israel, many elementary schools send hordes of school-children to plant new trees. It is estimated that upwards of 300 million trees have been planted by school-children since the state's inception. However, the Keren Kayemet, a national foundation similar to the Parks Commission, has to send out a vast number of employees to replant those trees, since school children understandably aren't very good at it. Also, many of those trees are promptly bulldozed to make way for new neighborhoods and roads.
The Fast of Esther — 13 Adar or Adar II.
A minor fast day from sunrise to sunset, this day commemorates Esther's fasting for three days during the Purim story and leads directly into the reading of the Book of Esther when Purim begins that night.
Purim — 14 Adar or Adar II.
A "minor holiday" in that work is not forbidden. The most joyous day in the Jewish calendar, and the holiday most obviously geared towards kids. The story of Purim is actually really cool, taking place around 300 BCE, and involves kings! Queens! Betrayal! Conspiracy! Poison! Sex! Humiliation! War! And 1,000 Elephants! Essentially, the evil Haman tries to convince King Ahasuerus (sometimes known as Artaxerxes or Xerxes - yes, possibly that Xerxes) to kill all the Jews. Needless to say, he doesn't win, thanks to the efforts of the noble Mordechai and Esther, and is in fact Hoist by His Own Petard.
On Purim, kids dress up in various costumes and roam around town giving presents to their neighbors and friends (so it's kind of like a reverse Halloween, though not as scary). More importantly, it's required to get drunk on Purim; according to the Talmud, one must be inebriated enough to not know the difference between "Blessed is Mordechai" and "Cursed is Haman". Overly sober rabbis have indicated that one can fulfill this just by going to sleep (since unconscious people don't know the difference either). Most other people have called them spoilsports and gotten drunk all the same.
- Among Orthodox Jewry there is actually a great deal of debate over what exactly this requirement for drunkenness means in a practical sense. The general consensus among Modern Orthodox rabbis is that those who can drink in a safe and responsible manner should have something to drink, perhaps even enough to make them appreciably (and pleasantly) drunk, but not so much that they literally can't differentiate between "Blessed is Mordechai" and "Cursed is Haman", probably because that level of intoxication also leads to blackouts, drunk driving, assaults, and all sorts of general badness.
In synagogue, the Book of Esther is read, and whenever Haman's name comes up, everyone in the synagogue makes a huge racket. Traditionally this was with graggers (noisemakers with a cylindrical handle that are turned to make noise) but nowadays you're likely to hear electronic beepers, cap guns, or just plain banging.
There's also a requirement to have a big honking feast in the evening, during which the people who aren't drunk yet often become so.
Also, it is forbidden to refuse a request for charity, so many people go collecting. Often these people are teenage boys in funny hats and various stages of inebriation, who sing and dance around your house, making the china wobble.
Food! Hamentashen are triangular pastries filled with jam or poppy seeds and are ubiquitous on Purim. The Hebrew name (Oznei Haman) mean "Ears of Haman". Try not to think about that too long. For young kids this is ignored and we tell them that Haman wore a three sided hat. This was most likely started by mothers sick of having to deal with their children not being able to sleep through the night until Pesach. The etymology of the Yiddish term, Hamentash, is unknown, with a great many possibilities under consideration.
Shushan Purim — 15 Adar or Adar II
People in cities that have been surrounded by a wall since the time of Joshua push Purim off by a day, celebrating it on this date instead. This includes Jerusalem and Shushan (for which the day is named),note as well as a widely varying list of other cities, depending on custom. This has also led to a great deal of debate about what constitutes "a city surrounded by a wall since the time of Joshua": besides which cities these were, do people living in the same municipality but outside the old walls count?note What if the walls were entirely destroyed and then rebuilt? What about a city with two or more walls concentrically (pretty common for a very long time; Rome is the most famous, but many cities followed the same pattern), one older and one more recent? Etc., etc., etc.
Passover — 15-22 Nisan (21 Nisan in Israel)
Taking place 30 days after Purim, Passover (or Pesach) is one of the big three holidays, and probably the second best-known after Chanukah. It commemmorates the exodus from Egypt over 1,000 BCE. As the Bible says, the Jews were led out of Egypt so quickly that their bread didn't have time to rise. The end result was matzah, which for Ashkenazi Jews is invariably a flat bread sort of like a cracker. Because of this, on Passover nothing leavened ("chametz") is eaten at all. Some Orthodox movements have latched onto Passover as a great place to introduce stringencies; so, for example, Ashkenazi Jews don't eat beans or rice, and many don't even allow matzah to come into contact with any liquid, for fear that there's a little uncooked dough inside that may rise. Sephardi and other Jews are for the most part free of this sort of thing, regarding the Ashkenazi stringencies as kind of silly, and several communities are known for their soft, bread-like matzah that is almost indistinguishable from regular bread—to say nothing of their fondness for rice dishes and plenty of legumes during Passover.
Before Passover, the house is cleaned scrupulously of all crumbs (this often turns into spring cleaning). The night before Passover, bedikas chametz (Search for Leaven) is done. This consists of turning out all the lights, going around with a candle (or flashlight), feather (or brush) and bag, and catching any crumbs you missed. To ensure you find something, 10 pieces of chametz (bread or possibly Cheerios) are put out beforehand. The next day, whatever chametz you have left is burned. Chametz which cannot be discarded is symbolically sold to a non-Jew and sealed off for the duration of the holiday.
Passover is seven (eight outside Israel) days long; the first and last (or outside Israel, first two and last two) days are "major holidays" while the middle ones are "Chol Hamo'ed".
On the first night (or first two outside Israel), a seder is held. This is a long, ritual-laden sequence which the family holds in their dining room. It involves discussion of the Exodus and Torah thoughts; specific foods eaten, such as matzah and maror, a bitter herb (usually lettuce, particularly romaine—which is not bitter at first, but becomes bitter after a while, representing the Hebrew experience in Egypt—but horseradish, endive, green onion, and parsley are also used), to remember the servitude; a meal; four cups of wine; and many songs. The whole thing is contained in a book called the haggadah ("telling"). Sedarim can last well past midnight.
The Last Supper in Christianity is generally held to have been a Passover seder, and in general, Easter falls quite close to Passover. The massive movement in the date of Easter is a result of having a Christian holiday map to the Jewish festival of Passover; the incessant debates over how to calculate the date of Easter is a result of the Christians refusing to just use the Jewish calendar to figure out the date already and rely on convoluted mathematics instead. Sects that just rely on Passover were declared heretical a long time ago and are mostly nonexistent. The name of Easter in many languages is based on the Hebrew Pesach (Passover): Latin and Greek Pascha gave rise to Spanish Pascua, Italian Pasqua, French Pâques, and Dutch Pasen (among others), and the Hebrew Pesach directly led to Arabic Id ul-Fiṣḥ.note
Food! Lots of stuff can't be eaten on Passover, leading to creative copies and workarounds. Potatoes and eggs are always popular, and potato starch is often used instead of flour. Egg noodles instead of normal ones, too. And some really awful candy and chocolate. Another flour substitute is matzah meal, essentially pulverized matzah. Unfortunately, matzah has adverse effects on the digestive system, so many an Ashkenazi Jew will spend at least the end of Pesach somewhat blocked. As noted above, this is one holiday where it's definitely better to be Sephardi; since the Sephardim never engaged in the vast multiplication of stringencies (particularly the ban on things resembling chametz) that the Ashkenazim do, many of them can go through Passover with their diets largely unchanged (albeit with more rice than might be usual in a week). Corn is another food that shows up on lists of foods Ashkenazim can't eat during Passover, which causes problems for everything in the United States that ends up having corn syrup in it, to where Coca-Cola and Pepsico have special new recipes for the Passover season and have unique yellow and white bottle caps (respectively) to show which of their products use sucrose instead of high fructose corn syrup.
Mimouna — 22 Nisan
Owing to All Jews Are Ashkenazi, Mimouna is practically unknown outside Israel - but is very popular there. It is a Moroccan Jewish holiday that occurs on the day immediately following the end of Passover (add one extra day outside Israel).
Mimouna is pretty much all about the food, effectively being a literal "breakfast" following the Passover restrictions. Moroccan Jews dress up in flashy traditional north-African clothes and engage in massive public feasts, music, and dances. Everyone is welcomed to the feast, including strangers and non-Jews. Israeli politicians — and especially Ashkenazi ones — never pass up the opportunity to arrive for a photo-op, portraying themselves as being "in touch" with their Moroccan constituents.
Food! Mimouna is characterized by a variety of sweet dishes, including some that are unleavened and some that can be quickly whipped up as soon as the Passover restrictions are lifted. The most famous of these is the Moufletta, which is basically a pancake (pan-fried flour and water) dipped in honey and other sweet spreads.
Sefirat Ha'Omer — 16 Nisan - 5 Sivan
The 49 days between Passover and Shavuot are known as Sefirat Ha'Omer (Counting the Omer). Each night, we count the days and weeks that have passed since the second day of Passover. During this time, when the Temple was standing, a special offering of Barley was given, known as the Omer (hence the name).
This time is also traditionally one of mourning, since in Talmudic times, a plague swept through the students of the great Rabbi Akiva, killing 24,000 of them. For three to four weeks (depending on your custom), we don't listen to music, shave our beards, cut our hair, or have weddings.
Yom Ha'Zikaron — 4 Iyar (3 Iyar if 4 Iyar falls on Thursday, 2 Iyar if 4 Iyar falls on Friday, 5 Iyar if 4 Iyar falls on Sunday)
Basically, it's Israel's equivalent to memorial day, and it's mainly observed there.
Yes, observed. Not celebrated, observed. It's a somber day of mourning and reflection, recognizing those soldiers who have died in service to Israel, as well as all the Jews killed in Pogroms since the 1870s, and it shows; Not only are all flags lowered to half-mast, all places of public entertainment closed, TV shut down, and radio only playing mood-appropriate songs, the entire country - even cars on highways - will stop everything and freeze in place for two minutes on 11 AM to observe a moment of silence, accompanied by a siren. Most Israelis will also visit memorials and graves of loved ones.
As you may guess, the utter idea of treating Memorial Day as a Holiday, like in the United States, does not sit well with Israelis at all.
Yom Ha'Atzmaut — 5 Iyar (4 Iyar if 5 Iyar falls on Friday, 3 Iyar if 5 Iyar falls on Saturday, 6 Iyar if 5 Iyar falls on Monday)
The celebration of the adoption of the Israeli Declaration of Independence on May 14, 1948, which, as you might guess from the date, fell on 5 Iyar 5708 according to the Hebrew Calendar. Although it's a national holiday in Israel, religious Zionists also celebrate it as a religious holiday outside Israel with their own celebrations.
There's barbecues, beach parties, fireworks, and the national flag hanging in every corner - but that's where similarities with the Fourth of July end. The celebrations begin on 20:00 the day before (which is Israel's Memorial Day) with a nationally-televised torch-lighting ceremony, where 12 noteworthy people come to Mt. Herzl near Jerusalem (the site of Israel's national cemetery, which includes Herzl's tomb) to, well, light torches that represent the 12 tribes of Israel.
After the ceremony, people gather at the main squares for mass rallies, which usually have a public sing-along and a fireworks display, followed by street parties deep into the night - but not before spraying snow-foam everywhere and waving flag-patterned inflatable hammers while on their way.
On Independence day itself, there's usually barbecues, beach parties, and hikes around the country. Army bases are open for visitors, and the Air Force does a fly-by above major cities - both are holdovers from the military parade the IDF used to hold in the first two decades of the State. The International Bible Contest is also held on this day.
Outside Israel, there are often carnivals, public events with speeches, dancing, and music (notable because it always takes place during the days of Sefirah, when music is usually prohibited), and treats in Jewish day schools.
Food! Meat. Lots and lots of meat, plus baked goods with blue-white food dye.
Lag Ba'Omer — 18 Iyar
The 33rd day of the Omer ("Lag" is 33 in Hebrew letters). A very minor holiday, but it's when the students stopped dying, so it's a happy day. The primary custom is to have a big bonfire (in Israel they're really big on this part), though there's something about archery as well (not many people do this).
Shavuot — 6-7 Sivan (in Israel only 6 Sivan)
One of the big three holidays, the only one to be only one (or two) days long. Shavuot (or Pentecost) takes place 50 days after Passover and commemmorates the giving of the Torah on Mt. Sinai. There are only two well-known customs associated with it. First, men stay up literally the entire night studying Torah. Morning prayers are done before sunrise, and often finish around 7:00 AM. Second, plant decorations are common (flowers, greens etc.) in both homes and synagogues.
Although on an importance level Shavuot is up near the top, for some reason it is one of the most-overlooked festivals for non-Orthodox Jews.
Food! It's customary to eat dairy products throughout the holiday (on either half the meals or all of them). There are a lot of explanations for this; one is that this is because right after the Torah, with its laws on meat and milk, were given, the Jews had to make their pots and pans kosher, so they couldn't eat meat immediately.
The Three Weeks — 17 Tammuz - 9 Av
The Three Weeks (sometimes known as Bein Ham'tzarim, "between the borders") is a time of mourning in the summer. It marks the time when the Temples were destroyed, and several other historical tragedies occurred then as well.
The first day is the 17th of Tammuz, which is a fast day. The three weeks afterwards are given mourning rituals: so, like in Sefirat Ha'Omer, no shaving, no music, no weddings, no haircuts.
The last nine days are called (oddly enough) the Nine Days, starting from the first of the month of Av. Additional restrictions are added - no eating meat, no drinking wine, no swimming.
The culmination is in Tisha B'Av, the Ninth of Av. This is a super-long fast day, beginning the evening before. We sit on the floor (or very low chairs or benches). The Book of Eichah (Lamentations) is communally read at night, and both at night and during the day, there are extended "Kinos" (also lamentations) read in the synagogue. During the day it's common to have speeches or (lately) video presentations emphasizing introspection and repentance.
Six days later, Tu B'Av, is a very minor holiday, with few actual customs associated with it. In Talmudic times it was a sort of day of matchmaking, which has been revived in recent years in modern Israel as an equivalent to Valentine's Day.
If you're wondering what Jews do on non-Jewish holidays, this guy pretty much sums it up (at least for Jews in predominately Christian areas). Note that even on non-Jewish holidays, food is still involved.
Among the non-Orthodox, there's also parties to be found on Christmas eve in major American cities, such as Jew'ltide and Heebonism.
In Israel, the foreign holidays celebrated by a majority of the population are New Year's (50% chance it's specifically the Russian Novy God - If it's not, it's called "Sylvester's"), and Valentine's. Naturally, there's a vocal minority that discourages the celebrations, with the argument that "Sylvester/Valentine/Novy God was an antisemite!"
Thanksgiving, Halloween, and U.S.-style Christmas are celebrated by most Anglo Olim, plus a siginificant proportion of teens and children in Tel Aviv. The rest of the population's reactions to them ranges from "indifference" to "these holidays are an evil virus of Uncle Sam and embracing them will result in the destruction of Israeli culture".