People ask me about Passover. I loathe explaining it, because I'm always afraid of my own ignorance, however; I did a good job in an email to Rick when he asked about the Seder. He also did a bit of research and I'll post that here, too.

From my email: The Seder is the Passover supper (there are three: two on the first two nights and one on the last, but reformed Jews usually only do the first, and sometimes the second).

Through the eating of specific foods, we commemorate the suffering and blessings that our ancestors survived in their flight from Egypt. Passover itself is refering to the final plague set upon the Egyptians... the killing of the first born son. Jews marked their doors with lamb blood to signify their faith and so, the Angel of Death passed over their houses.

In Christian terms, the Seder is what Jesus celebrated with his disciples when they had the Last Supper.

From the website, detailing what is set upon the Seder plate:

Maror
Bitter Herbs (usually horseradish) symbolize the bitterness of Egyptian slavery

Karpas
Vegetable (usually parsley) is dipped into salt water during the seder. The salt water represents the tears shed during Egyptian slavery.

Chazeret
Bitter Vegetable (often lettuce) is often used in addition to the maror as a bitter herb

Charoset
Apple, nuts, and spices ground together and mixed with wine are symbolic of the mortar used by Hebrew slaves to build Egyptian structures

Zeroa
The Shankbone is symbolic of the Paschal lamb offered as the Passover sacrifice in biblical times

Beitzah
The Roasted Egg is symbolic of the festival sacrifice made in biblical times

I hope that enlightens a few.