Jewish holidays always start in the evening a day before the date specified on most of our calendars. As the Roman calendar, where a day starts at midnight, the Jewish day begins at sunset and ends at sunset. Therefore, at nightfall the Holidays are set to end, this is as soon as it becomes dark about after the sunset. As noticed, the holidays may be celebrated for more one extra day as specified in the Bible. This is explained below.
In the Jewish calendar, each month begins on the new moon since it is lunar. From just a mere observation, the new months were determined. Once a new moon was seen, the Sanhedrin marked that day as the start of the new month and messengers were sent to inform the people. Due to distance barrier and lack of fast communication methods, the communities living at the far end, could not be notified of the new day which here happens to be the first day of the month, so they would not know the exact day to celebrate. But they already knew that the current month would last for 29 to 30 days. So if they used to celebrate the holiday for two days to cover which is which. To maintain this as a custom of their ancestors, even after getting a more updated calendar this practice was continued and celebration for two days was maintained.'
The Passover holiday marks the Exodus of Jews from Egypt. It is celebrated for seven or eight days in accordance to the branch of Judaism, from a full moon night in April. Easter usually overlaps with Passover. Jews avoid bread and grain or flour products or any other product during this holiday; this is to remember their ancestors from Egypt were in a hurry, and there was no time for the bread to ferment and rise so they had to take unleavened bread.
Strictly, Jews do not observe the standard working-day schedule such as going to work, school or even doing business on both the first and last two days of Passover as it is a requirement from Jewish law. Just like all other Jewish holidays, Passover begins at the evening a day before the calendar.
Rosh Hashanah is marked as the first day of the Jewish Year holiday the day marks a start of the new Jew new year. This holiday lasts for either one or two days, in accordance to one's Judaism branch.
Rosh Hashanah holiday is a happy and festive just like the 'New Year', but it's somewhat more intensive. Like the 'New Year', it calls for people to look back at the past year where one is supposed and make resolutions for the following year. It is also aimed at mentally preparing people for the upcoming holiday, Yom Kippur.
Many of the Jews even those who do not go to synagogue any other time of year will go to synagogue on this day. Just like the "twice-a-year Christians" who attend the church only on Christmas and Easter, there are also "Twice-a-year Jews" visit the synagogue only on Rosh Hashanah and Yom Kippur.
The Jewish day of atonement is marked as Yom Kippur. It is a day of full fasting and repentance to reunite themselves with their God for the possible mistakes may have been made in the just ended year. Yom Kippur is only aimed to atone for sins between only man and God, not for sins against another person.in order To atone for sins against a fellow man, one must first seek out their reconciliation, and by accepting and correcting the wrongs done against each other if possible. Yom Kippur is scheduled on a ninth day counting from the first day of Rosh Hashanah. So counting from the Roman calendar it is usually dated around late September or early October of each year. The ten days period between Rosh Hashanah holiday and Yom Kippur holiday is the traditional is meant for forgiveness from one's friends and neighbours so that on Yom Kippur one can attain clemency and cleansing for all transgressions from God. This act of atonement makes a claim that human beings can change and improve. There is no addition for an extra day to this 25-hour fast.
Most people (Jews) take off from work or school on this day. For synagogues, it is the busiest day of the year even though many synagogues charge for tickets to this day's services. Many will also want to leave work early the night before, so they have time for a large, slow meal before this 25-hour fast.