Pesach is commonly known as the holiday of Passover, which begins on the 15th day of the Jewish month of Nissan, and is the first of the three “spring holy days”, the other two high holy days being Shavu'ot and Sukkot. The word Pesach comes from the root Peh-Samech-Chet which means “pass over” which speaks of how God passed over the Hebrews in Egypt during the plague that killed the firstborn males of every human and beast.
The most significant part of this holiday is the fact that when observing it a family must remove all the leavening (Chametz) from the house, which means no store bought bread. The removal of the yeast is to symbolize the removal of pride and sin out of one's life; it also shows that the people who fled from Egypt didn’t have time to let their bread rise.
The term chametz also includes five types of grain that can be eaten under the strict rule that it has to be finished cooking 18 minutes after coming into contact with water. The five grains chametz grains are wheat, rye, barley, oats and spelt. Orthodox Jews of Ashkenazic background also avoid rice, corn, peanuts, and legumes as if they were chametz. The additional of these items is referred to as kitniyot. These items are normally used to make bread, thus use of them was prohibited to avoid any confusion. Instead of chametz grains, Jewish people tend to use potatoes and matzah during the Passover to take the place of traditional bread.
A few weeks before Pesach starts, a family must prepare their house for the Passover by cleaning it from ceiling to floor, and on the morning before the seder the family goes through the house and finds anything that is chametz and burns it.
The day before Pesach is known as the Fast of the Firstborn, a fast for all firstborn males that commemorates the fact that the firstborns of the faithful people in Egypt were not killed by the final plague.
Pesach lasts for seven days (eight days outside of Israel). The first and last days of the holiday (first two and last two outside of Israel) are days on which no work is permitted. Work is permitted only on the days inbetween, and those inbetween days are called Chol Ha-Mo'ed; as are the intermediate days of Sukkot.
The content of the seder can be summed up by the following Hebrew rhyme:
1. Kaddesh: Sanctification.
A cup of wine is poured and a blessing is said over wine in honor of the holiday, afterward everyone drinks the wine. Then a second cup is poured.
2. Urechatz: Washing.
Everyone washes their hands this time without a blessing,
in preparation for eating the Karpas.
3. Karpas: Vegetable.
A vegetable is first dipped in salt water and then eaten; the vegetable symbolizes the humble roots of the Jewish people as the
salt water is said to symbolize the tears shed under the oppression of slavery. Parsley is a good for this because as you shake it
the salt water drops off like tears.
4. Yachatz: Breaking.
Someone takes one of the three matzahs that are on the table and brakes it.
One part is returned to the pile, the other part is set aside for later.
5. Maggid: The Story.
Then someone reads the story out of Exodus about the escape from Egypt
and the original Pesach. Then the youngest child asks four traditional questions, a set of questions that are intended to spark an interest in participating in the seder. After the maggid, a blessing is recited over the second cup of wine and
it is drunk.
6. Rachtzah: Washing.
Again everyone washes their hands, this time a
Blessing is recited in preparation for eating the matzah.
7. Motzi: Blessing over Grain Products.
After washing your hands, the ha-motzi blessing, a generic blessing for the
bread or grain products used in a meal, is recited
over the matzah.
8. Matzah: Blessing over Matzah.
After the motzi is recited, a specific blessing for matzah is recited, and a
bit of matzah is eaten by all.
9. Maror: Bitter Herbs.
After the matzah is eaten another blessing is recited over a bitter vegetable which is usually raw horseradish; though sometimes romaine
Lettuce is used, and it is eaten. This symbolizes the
bitterness of slavery. The maror is dipped in charoset which is
a mixture of apples, nuts, cinnamon and wine;
which symbolizes the mortar used by the Jews to
build during their slavery. Note that there are two
bitter herbs on the seder plate: one labeled Maror
and one labeled Chazeret..
10. Korech: The Sandwich.
Rabbi Hillel was of the opinion that the maror should
be eaten together with matzah and a piece of the paschal
offering in a sandwich. In his honor, some Jews eat
maror on a piece of matzah, with some charoset
(but since there are no animal sacrifice anymore, there is
no paschal offering to eat). The bitter herb that is set aside and labled "chazeret" should be used in the making of this sandwich.
11. Shulchan Orech: Dinner.
Everyone gathers around for the meal. Since there is no particular
requirement regarding what to eat at this meal
(except, of course, that chametz cannot be eaten), it is usually very lively.
12. Tzafun: The Afikomen.
This part has the potential of being very entertaining to kids, since in certain families the parents make an effort to invent ways to make their children want to pay attention through what could be boring ritual to a five year old. The piece of matzah that was separated earlier is suppose to make a reappearance, this can be made into a game by having someone hide it and having everyone else look for it. Traditionally the matzah is eaten as
"dessert," the last food of the meal.
13. Barech: Grace after Meals.
The third cup of wine is finally poured, and birkat ha-mazon
(grace after meals) is recited. This is similar to the
traditional words that would be said on any Shabbat. At the
end, a blessing is said over the third cup and it is
drunk. The fourth cup is then poured, including a cup traditionally set
aside for the prophet Elijah, who is supposed to
proclaim the Messi.ah, and is supposed to come back on
Pesach to do this. The door is opened for a while
at this point, traditionally out of hope that Elijah has come back.
14. Hallel: Praises.
At this point several psalms are recited, and a final blessing is recited
over the last cup of wine and it is drunk.
15. Nirtzah: Closing.
The closing is a simple statement that the seder has been completed,
and with a wish that next year, Pesach may be celebrated in Jerusalem. This is followed by various hymns and stories.
Information gleaned from http://www.jewfaq.org/holidaya.htm
Iconoplast tells me that Coke makes a variety of its products during passover specially for select markets to be kosher, the corn syrup is replaced with cane or beet sugar. I am sure there are other products that are modified around passover to be kosher.