Jewish holidays are defined by the
Hebrew calendar. Christian holidays are defined by the
Gregorian calendar for Catholics and the
Julian calendar for Orthodox. Druze holidays are also defined by the Gregorian calendar, with the sole exception of
Eid al-Adha which is also celebrated by Muslims (and therefore defined by the
Lunar Hijri calendar). Secular observances which are common to all religions are defined by the Hebrew calendar if they are of a uniquely national nature (such as
Yom Ha-Atzmaut), and by the Gregorian calendar if they are of a global or international nature (such as
Victory in Europe Day). The following are official holidays imposed by government authorities, except in cases of emergency or entities that require daily operational activities. ==Optional holidays or Observances==