On Yom Tov night, just as on Friday night, there is a mitzva to recite kiddush over a cup of wine, at the site of the festive meal. The Sages ordained that the sanctity of the day be invoked in prayers and at meals, for the sanctity of the day is manifest through both body and soul.
The content of kiddush is similar to that of the Amida’s middle berakha, and its conclusion is identical: “Blessed are You, Lord, Who sanctifies Israel and the seasons” (section 3 above). One first recites the berakha over wine and then the berakha over the sanctity of the day. Afterward She-heḥeyanu is recited, in which we thank God “Who has given us life, sustained us, and brought us to this time.” If one forgot to recite She–heḥeyanu during kiddush, he can do so when he remembers, anytime during the festival. It is not necessary to have a cup of wine for it (MB 473:1).
The seventh day of Pesaḥ is the only Yom Tov when She-heḥeyanu is not recited at kiddush, because it is not considered a self-contained festival. Thus, the She-heḥeyanu recited on the first day covers the last day as well. In contrast, on Shemini Atzeret one does recite She-heḥeyanu, as it is a festival in its own right (RH 4b).
On Yom Tov of Sukkot, the berakha of Leishev Ba-sukka is added to kiddush since at this time we begin to fulfill the mitzva of sitting in the sukka.
The Sages ordained that Yom Tov kiddush be said by day as well as at night, as on Shabbat, in order to honor the day. Since the sanctity of Yom Tov had already been invoked in the nighttime kiddush, it is not repeated during the day. Rather, the daytime kiddush is limited to the berakha over the wine. It is customary to add a verse beforehand which relates to the holiday. This kiddush is referred to as Kidusha Raba (the great kiddush), which is a euphemism, since it is the nighttime kiddush at the beginning of Yom Tov which is the important one. It is then that we invoke the sanctity of the festival (MB 289:3). The rest of the laws pertaining to kiddush are explained in Peninei Halakha: Shabbat (ch. 6).
As we have seen (1:7 above), it is a mitzva to eat two festive meals on Yom Tov, one by night and one by day. At each meal there is a mitzva to eat bread. Yom Tov meals must be even better than Shabbat meals because there is an additional mitzva of simḥa. The daytime meal is more important than the nighttime meal.