What are there holy days?

Answer 1

I assume this means "Why" are there holy days.

Holy days are made to commemorate significant milestones in a religion. They remind the people of their heritage and of significant events in their belief structure. For example, in Roman Catholicism, the Solemnity of the Annunciation was meant to commemorate the moment when the Arch-angle Gabriel announced that the Blessed Virgin would give birth to the son of God. Since this is one of the most important stories in the religion, it is commemorated with a holy day so that people will remember the importance of the event and to worship God. Another example is the feast of St. Peter in Roman Catholicism. This is meant to commemorate one of the most important figures of the church. Since he was such an important figure, the church dedicates a day to him so that people will remember him and look to his example in their daily lives. The same principal applies to other religions as well.

In Judaism, the festivals have the shared purpose of "remembering the Exodus from Egypt" (as stated in the kiddush over wine).

In addition, Passover is a Thanksgiving to God for the barley-harvest, Shavuoth is a thanksgiving to God for the wheat-harvest, and Sukkoth is a thanksgiving to God for the ingathering of grain.

Shavuoth also celebrates the Giving of the Torah on Mount Sinai, and Sukkoth remembers God having protected the Israelites in the wilderness.

It may also be noted that it is instinctive and a moral and emotional need and imperative to celebrate in front of God every so often. This was Cain's motivation in making his offering in Genesis ch.4 without having been commanded.

Had God not given the Israelites the Torah-festivals, they might instinctively seek out those of the Canaanites, which the Torah warns against (Exodus 34:15) immediately before listing the Jewish festivals (in the following verses).