These fairly recent additions to the Jewish calendar bring with them new rituals that are already deeply rooted in Jewish communities around the world.
There are a handful of holidays that have entered Jewish life in the latter half of the 20th century. For the most part, these holidays are associated with the two major historical events shaping Judaism in the mid-20th century: the Holocaust and the rebirth of the State of Israel. They include both joyous and sad observances.
Yom Hashoah– Holocaust Remembrance Day–is observed one week after the conclusion of Passover, on the 27th of Nissan. Significantly, it is also halfway between the first day of the Warsaw Ghetto uprising–which began on the first day of Passover in 1943– and Yom Ha’atzmaut, Israel’s Independence Day. This date, chosen by the Israeli government, emphasizes the nature of Jewish opposition to disaster. While the rituals for this holiday are still being created, it is a solemn day that is widely observed wherever Jews live.
Yom Hazikaron–Israeli Memorial Day–is observed one week after Yom Hashoah and one day before Yom Ha’atzmaut. It is a quintessentially Israeli holiday, commemorating all the soldiers who fell in defense of Israel from the Israeli War of Independence in 1948 to the present. While it is often acknowledged outside of Israel, it is in Israel itself that this holiday unites the whole country in its somber observance.
Material excerpted from http://www.myjewishlearning.com/.