On Passover, Jews the world over remember the harrowing experience of the Exodus from Egypt by eating matzah. 

You are not to eat any chametz with it; for seven days you are to eat it with matzah, the bread of affliction, for you came out of the land of Egypt in haste. Thus you will remember the day you left the land of Egypt as long as you live. (Deuteronomy 16:3)

There are many types of matzah available during the week-long holiday of Passover, but certain types can only be eaten at certain times, and certain types of Jews only consume certain types of matzah. 

What is matzah?

Matzah is the unleavened bread that Jews eat during Passover in the Spring when leavened food, called chametz, is forbidden. Three pieces of matzah are used during the Passover seder, and Jews continue to eat matzah throughout the week of the Passover holiday. 

This bread is more like a cracker for Sephardic and Ashkenazic Jews, although Iraqi and Yeminite Jews have a matzah that is soft and more like a tortilla or Greek pita. It is prepared over an 18-minute period with water and grain flour mixed together and then baked either by machine or by hand. 

Called the "bread of affliction," matzah also is known as "poor man's bread," or lechem oni, because it is meant to remind Jews to be humble and not forget what life was like while in slavery. 

The Origins of Matzah

Matzah appears several times in the Torah in relation to the Exodus of the Israelites from Egypt. 

• Exodus 12:8 | That night, they are to eat the meat, roasted in the fire; they are to eat it with matzah and maror. 

• Exodus 12:8 | From the evening of the fourteenth day of the first month until the evening of the 21st day, you are to eat matzah. 
• Deutoronomy 16:8 | For six days you are to eat matzah. On the seventh day, there is to be a festive assembly for the Lord your God; do not do any kind of work. 

What is shmura matzah? 

Shmura, which means guarded in Hebrew, is matzah made from grains that have been supervised from harvest to baking to make sure that absolutely no fermentation has taken place. This type of matzah is suitable for eating on the first night of Passover during the seder, and it can be made by hand or by machine. 

Many Haredi or ultra-Orthodox Jews will only use hand-made shmura matzah at the Passover seder.

Wheat, Spelt, and Rye Matzah

These types of matzah are quite literally only the grain flour and water mixed together and baked -- all within a maximum of 18 minutes. These matzot (the plural of matzah) are watched very carefully from the moment the grain is placed with water to make sure that the process lasts no longer than 18 minutes. Any longer, and it becomes chametz.

These types of matzot are used during the Passover seder and eaten throughout the week as they allow Jews to make the HaMotzi blessing over a meal. 

Although for years it was said that the only "real" matzah that satisfied the commandment was that made with wheat flour, many who are allergic to wheat consume spelt or rye matzah, which is easier on the digestive system. 

Oat Matzah

There are many who will not consume oat matzah to satisfy the commandment to consume matzah at the Passover seder. Chabad Jews, for example, believe that the oats must be heated before they are processed and used in the making of gluten-free oat matzah. 

However, for those suffering from Celiac Disease and other allergies, gluten-free oat matzah is the only available option. As such, there are several rabbis, including Rabbi Kestenbaum, who have both approved and participate in the creation of gluten-free oat matzah. When in doubt, speak with your rabbi. 

Egg Matzah

This type of matzah is made with fruit juice, but not necessarily with egg itself. There is a custom among Ashkenazic Jews not to eat them during Passover. The elderly, infirm, and children, who have difficulties digesting regular matzah are allowed to consume egg matzah, although it will not satisfy the mitzvah to consume matzah at the Passover seder.

The question over egg matzah relates to whether fruit juice causes the same reaction as water when mixed with grain flour. This discussion comes from the Talmud, which says that liquid food extracts (like fruit juice) do not cause flour to leaven the way that water does. The ultimate ruling on the issue comes from Rabbi Joseph Karo, the author of the Code of Jewish Law, who granted permission for the use of any matzah made from non-water-based dough on Passover (Orach Chaim 462:4).

Potato and Rice Matzah

More like chips than crackers or bread, potato and rice matzah cannot be used for the seder or to satisfy the HaMotzi meal blessing.