Begins at sundown on April 22.
Pesach, known in English as Passover, is one of the most commonly observed Jewish holidays, even by otherwise non-observant Jews. Pesach begins on the 15th day of the Jewish month of Nissan. It is the first of the three major festivals with both historical and agricultural significance (the other two are Shavu'ot and Sukkot).
Passover lasts for seven days (eight days outside of Israel). The first and last days of the holiday (first two and last two outside of Israel) are days on which no work is permitted.
The name “Passover” is derived from the Hebrew word Pesach which is based on the root “pass over” and refers to the fact that G-d “passed over” the houses of the Jews when he was slaying the firstborn of Egypt during the last of the ten plagues. Passover is also widely referred to as Chag he-Aviv (the "Spring Festival"), Chag ha-Matzoth (the "Festival of Matzahs"), and Zeman Herutenu (the "Time of Our Freedom").
Source Judaism 101