The Five Mitzvot of the Seder
Although the singing of “Dayeinu” and “Chad Gadya” are important parts of any Pesach Seder they are not among the obligatory components of the evening. Contrary to popular misconception, there are only five mitzvot that are absolutely essential which one must be sure to perform at the Seder. Two of these mitzvot are biblical in origin and three of them are rabbinical in origin.
V'higadeta – The Mitzva to Relate the Story of Yetziat Mitzrayim
One of the biblically required mitzvot of the Seder night is to relate the story of yetziat mitzrayim, the Exodus and redemption from the slavery of Egypt.. This mitzva is based on the verse “And you shall relate it [the story of the Exodus] to your son on that day.” The mitzva is not only to teach one's children the story of the Exodus, but it also applies to anyone that one has the opportunity to relate the story to, such as the guests at one's Seder. In theory one can discharge this mitzva in any manner that one chooses but universal custom is to follow the arrangement and narrative as it is presented in the Haggada.
Although there is actually a mitzva to recall yetziat mitzrayim every single night of the year, Pesach night is different in that one is required to do so verbally and in a question-and-answer format.  Even one who is alone for the Seder is still required to recite the Haggada audibly to oneself. While the wording of the verse seems to imply that a father is personally obligated to relate the story of yetziat mitzrayim to his son, it is not always necessary that the father be the specific person to do so. It is permitted to appoint a shaliach, an agent, to ensure that one's son is told the Pesach story on Seder night.  For example, one fulfills the mitzva to teach one's children through a grandparent or anyone else who might be leading and explaining the Seder. Women are equally obligated in this and all other Seder night mitzvot, as they too were redeemed from Egypt. It is a matter of dispute, however, whether women are obligated by Torah law to relate the story of yetziat mitzrayim or if their obligation is rabbinical in nature.
Even though as a general rule it is preferable to pray in Hebrew even if one doesn’t understand the meaning of the words rather than to pray in any other language, it is imperative, however, that one understands the story of the Exodus. As such, one who is not fluent enough in Hebrew to understand the Haggada is required to recite it in English (or any other language one understands) in order to properly fulfill the mitzva. While it is ideal, of course, to recite the entire Haggada, one must be sure to at least recite the portion of the Haggada which begins with the words “Rabban Gamliel used to say.” This is especially relevant for women who often find themselves preparing the festive meal rather than sitting at the Seder table.
One must endeavor to recite the Haggada with a feeling as if one is presently leaving Egypt oneself. As a further display of freedom, the Haggada should be recited while comfortably seated, though not while reclining. One should make every effort to keep the children awake for as long as possible in order that they should experience as much of the Seder as possible. It is interesting to note that one who is visiting his children in Israel over Pesach and is observing a second day of Yom Tov will be obligated in the mitzva of "And you shall relate it [the story of the Exodus] to your son on that day" on the second night of Pesach just like the first night.
While on a regular Shabbat or Yom Tov one is generally required to eat one's meal immediately following Kiddush without delay, the Pesach Seder is somewhat of an exception to this rule. Between the recitation of Kiddush and the start of the festive meal there is often a delay of quite some time, even hours, while one is reciting the Haggada. Nevertheless, since the recitation of the Haggada is considered to be a form of preparation for the meal it is not considered a hefsek, a forbidden interruption, between the Kiddush and eating.
Matza – The Mitzva to Eat Matza on the First Night of Pesach
The other biblically required mitzva that one must fulfill at the Seder is that of eating matza, as the Torah says: “In the evening you shall eat matzot.” While it is ideal for one to eat two kezaitim of matza (about 3 ounces) when matza is first eaten at the Seder (one kezayit from the top matza and another from the middle broken matza), one fulfills the mitzva with even a single kezayit of matza (about 1.5 ounces). It is recommended that one put the two kezaitim of matza into one's mouth at once, swallowing one kezayit at a time.
The matza must be eaten while reclining. It is preferable to eat the matza within a three minute time span, though many authorities allow up to nine minutes under extenuating circumstances. When eating the matza one should have in mind that one is performing a mitzva of the Torah. In our day and age, due to the lack of a functioning Beit Hamikdash, the mitzva of matza is the only mitzva of the Torah that one fulfils through eating. It is also preferable for one to officially own the matza that one is using for the mitzva. Although there are other points in the Seder where one will be prompted to eat more matza, it is at "Motzi Matza" that one discharges the actual mitzva. Nevertheless, one earns a mitzva for every bite of matza one eats throughout the first night of Pesach and according to some opinions, there is a mitzva to eat matza the entire week of Pesach, as well.
The Four Cups of Wine
The most prominent rabbinical mitzva of the Seder night is the requirement to drink four cups of wine at the specifically designated points in the Haggada. These four cups of wine represent the four different expressions used by the Torah to illustrate the redemption of the Jewish people. Another interpretation has it that the four cups of wine are intended to recall the four times that the word "kos" appears in the narrative of Pharaoh's dream. It is also taught that the four cups of wine represent the four forms of retribution that God will avenge upon the nations of the world in the Messianic era.
The wine goblets used at the Seder must hold at least 3.3 ounces, though widespread custom is to ensure that they hold at least 4.5 ounces of wine. Some authorities even require 5.5 ounces. One who cannot afford to purchase wine for the four cups is required to appeal to a charity for the money.
It is preferable for one to drink the entire cup of wine each time, though it suffices to merely drink the majority of the cup. It is permitted to use white wine at the Seder but red wine is to be preferred. It is preferable to use non-mevushal, uncooked, wine for the four cups of the Seder. The four cups must be drunk at the specific points in the Haggada where they were instituted. Drinking the four cups of wine at the Seder is among the mitzvot which are considered to be in the category of pirsumei nisa, publicizing the miracle of the Exodus.
One should make great efforts to use wine rather than grape juice for the Seder even if it means some physical discomfort, though one need not make oneself sick. Even mixing wine and grape juice is preferable to using exclusively grape juice for the four cups. In an emergency, one can use any chamar medina for the four cups of "wine".Chamar medina is generally defined as a beverage worthy of being served to guests. It must also be a beverage that one drinks simply to enjoy its taste and even when not thirsty.
As the Seder officially begins with the recitation of Kiddush, which is also when the first of the four cups of wine is drunk, one must be sure not to commence Kiddush before dark. It is customary to arrange that Seder participants not pour their own wine but rather have it poured by someone else as a symbol of freedom and royalty.
Unlike most other mitzvot of the evening, a blessing is not recited upon the mitzva of the four cups of wine. Among the reasons for this is that a blessing is only recited upon mitzvot which are completely discharged at one time. The mitzva of the four cups, however, is a mitzva which is fulfilled at intervals throughout the evening with a significant delay between each cup. Another reason cited that a blessing is not recited is out of concern that one may get drunk or otherwise fall asleep and not properly complete the mitzva at all.
Marror – Bitter Herbs
Eating marror, bitter herbs, is also one of the rabbinical mitzvot of the Seder. The marror is intended to recall the suffering that the Jewish people experienced as slaves in Egypt. One should proceed to the eating of the marror without delay once one has eaten the matza. Marror is actually one of the more enigmatic mitzvot of the Seder in terms of which vegetables qualify to be used in fulfillment of the mitzva. Although the Talmud lists five species of vegetables which are acceptable for use as marror, there is actually some uncertainty regarding their present-day identity. Common custom is to use either romaine lettuce, horseradish, or endives for marror.
Although horseradish is certainly one of the valid species for use as marror, many people mistakenly use the commercial white or red horseradish that comes in a glass jar for this purpose. While eating this form of horseradish is certainly a grueling and bitter experience, one actually does not fulfill the mitzva with these products at all. This is because they are not one-hundred percent pure horseradish as they often including beets, sugar, vinegar, and other ingredients. So too, these jarred horseradishes also include preservatives, and the like. The mitzva of marror may only be fulfilled with raw vegetables, nothing processed or preserved. When using horseradish root for marror the horseradish should be grated.
It seems that the consensus of most halachic authorities is that one should use carefully washed, insect-free romaine lettuce for marror. It is explained that although romaine lettuce is not particularly bitter, it does have a bitter aftertaste. This is symbolic of the sojourn of the Jewish people in Egypt which began as a sweet experience and later tuned into a bitter one. Alternatively, although the leaves of romaine lettuce are not necessarily bitter, the stems, especially when left in the ground, turn hard and bitter which qualifies romaine lettuce as a bitter herb. Finally, the Hebrew word for lettuce is "chassa" meaning "mercy" which recalls God's decision to redeem the Jewish people from Egypt. Some rabbis were known to even use the sweetish iceberg lettuce for marror. Those who seek a truly grueling and bitter experience can use raw horseradish root, an option favored by many authorities, as well.
One must eat a minimum of a kezayit (about 1.5 ounces) of marror at the Seder, which can be a combination of lettuce and horseradish should one so desire. One who is unable to acquire any of the vegetables suitable for marror or is simply unable to eat the required amount should at least eat any bitter vegetable at the Seder in order to participate in the mitzva in some way, though the accompanying blessing is not recited. So too, one who has no sense of taste should not recite a blessing when eating marror.
One should use some of the marror from the Seder plate towards the amount of marror that one is required to eat. The marror should be dipped in the charoset mixture before eating it, though one should be sure to shake off any charoset remains. Contrary to popular misconception, there does not seem to be a mitzva, certainly not a requirement, to eat Charoset at any time. The entire kezayit of marror should be eaten at once if possible. One does not recline while eating the marror. The kabbalists teach that when eating the marror one should have in mind that it serve to atone for any forbidden foods that one may have eaten throughout the year.
The Recitation of Hallel
The recitation of Hallel is the final rabbinical mitzva of the Seder. These special prayers focus on praise and thanksgiving to God for having taken us out of Egypt. In what is a glaring departure from normal practice, the Hallel at the Seder is divided up, with some of it being recited before the meal and some of it being recited after the meal. It is important that one understands the words of the Hallel in order to properly fulfill the mitzva. It should also be sung or at least recited out loud. It is permitted to recite the Hallel in a place other than where the Seder was held if need be. Along with the eating of the afikoman, one is advised to complete the recitation of Hallel before midnight, as well. Three or more people reciting Hallel together should appoint one person to lead the sections which are customarily recited responsively.
 Rambam, Hilchot Chametz U'matza 7:1.
 Shemot 13:8.
 Minchat Chinuch 21.
 Rambam, Sefer Hamitzvot 157; Piskei Teshuvot 473:7.
 OC 473:7.
 B'tzel Hachachma 6:67; Teshuvot V'hanhagot 2:236.
 OC 472:14; Chayei Adam 130:12. See Rivevot Ephraim 1:312 and Rivevot V'yovlot 2:291.
 The Sefer Hachinuch (Mitzva 21) is of the opinion that women are required by the Torah, whereas the Rambam (Hilchot Avoda Zara 12:3) is of the opinion that their obligation is rabbinical.
 OC 101:4; but see Sefer Chassidim 588 and 785 for a dissenting view.
 Rema, OC 473:6, Rivevot Ephraim 1:302:2.
 Kitzur Shulchan Aruch 119:4.
 Pesachim 116b; Rambam, Hilchot Chametz U'matza 7:6.
 Shulchan Aruch Harav, OC 473:48
 Mishna Berura 472:50.
 Although many authorities disagree, this writer is of the opinion that visitors to Israel should keep only one day of Yom Tov as per: Shulchan Aruch Harav, OC 496:11, Biur Hagra, OC 496:11, Chacham Tzvi 167, and Yabia Omer 6:40. Historically, from the time of Chazal onwards, visitors to Israel kept only one day. See also Ir Hakodesh V'hamikdash 3:19; Devar Chevron 2:535.
 Nitei Gavriel, Hilchot Pesach 83:27.
 Aruch Hashulchan, OC 273:4.
 OC 476:7. See Shemot 12:18.
 OC 475:1
 Shulchan Aruch Harav, OC 475:8; Mishna Berura 475:11, Biur Halacha; Orchot Rabbeinu 2 p. 70
 Magen Avraham 475:4.
 OC 275:1.
 OC 475:1; Kitzur Shulchan Aruch 119:5.
 Igrot Moshe, OC 4:41.
 Mishna Berura 475:34.
 Chatam Sofer, CM 196, cited in Nitei Gavriel, Hilchot Pesach 90:n28
 OC 454:4.
 Nitei Gavriel, Hilchot Pesach 90:26; Avnei Nezer, YD 338:13. See also Gevurat Ari, Yoma 44b.
 Mishna Berura 539:24.
 Pesachim 108b.
 Levush 472:8; Shulchan Aruch Harav, OC 472:14; Mishna Berura 472:43. See Shemot 6:6.
 Rashi, Pesachim 108a; Yerushalmi Pesachim 10:1. See Bereishit 40. See also Rivevot Ephraim 1:298:6.
 Yerushalmi Pesachim 10:1. See Yirmiyahu 55.
 Pesachim 99b.
 Mishna Berura 472:30,33; Shulchan Aruch Harav, OC 472:19.
 OC 472:9; Mishna Berura 472:33.
 OC 472:11.
 Kitzur Shulchan Aruch 77:6.
 OC 472:8.
 Maggid Mishna, Hilchot Chanuka 4:12; Rivevot V'yovlot 4:112.
 Nedarim 49b; OC 472:10.
 Mishna Berura 472:35; Teshuvot V'hanhagot 2:243.
 Mishna Berura 472:37; Igrot Moshe, OC 2:75.
 Igrot Moshe 2:75.
 OC 472:1; Mishna Berura 472:5.
 OC 473:1; Kitzur Shulchan Aruch 119:2; Kaf Hachaim, OC 473:31.
 Elya Rabba 472:8.
 Pekudat Elazar (Ben-Tuvo) 473. See also Rivevot Ephraim 8:221 for more on this.
 The mitzva of marror is a Torah level mitzva when eaten together with the Korban Pesach. In the absence of the Beit Hamikdash eating marror is only required by rabbinical law.
 OC 475:1.
 Pesachim 39a.
 OC 473:5.
 Shulchan Aruch Harav, OC 473:30; Chacham Tzvi 119; Mishna Berura 473:42.
 Magen Avraham 473:14; Chacham Tzvi 119; Shaarei Teshuva 473:11; Mishna Berura 473:34, 42.
 Chacham Tzvi 119.
 It is interesting to note that Rabbi Herschel Schachter subscribes to the view that horseradish is not one of the five vegetables that are acceptable for marror. He notes that the other vegetables on the list are green leafy vegetables and are "bitter" rather than "sharp".
 OC 473:5.
 Levush 473; Chacham Tzvi 119; Shulchan Aruch Harav, OC 473:30; Mishna Berura 473:34.
 The practice of Rabbi Aharon Kotler, cited in Rabbi Shimon Eider, Halachos of Pesach (Jerusalem: Feldheim, 1998).
 Pesachim 39b; Magen Avraham 473:12.
 Kitzur Shulchan Aruch 119:7.
 OC 473:5.
 Kitzur Shulchan Aruch 119:7; Avnei Nezer 383.
 Yashiv Yitzchak 8:16.
 Piskei Teshuvot 475:5.
 OC 475:1; Mishna Berura 475:17.
 Pesachim 114a; Pesachim 116a. See also: http://www.koltorah.org/ravj/charoset.htm.
 Magen Avraham 475:4.
 OC 475:1.
 Nitei Gavriel, Hilchot Pesach 54:19.
 Pesachim 116b.
 Nitei Gavriel, Hilchot Pesach 102:4.
 Rema, OC 480:1.
 OC 477:1; Mishna Berura 477:7; Rivevot Ephraim 7:153
 Rema, OC 479:1.