section_path: Components/Days
section_name: Days
paragraph_text: Days
  
  Based on the classic rabbinic interpretation of Genesis 1:5 ("There was evening and there was morning, one day"), a day in the rabbinic Hebrew calendar runs from sunset (the start of "the evening") to the next sunset. Similarly, Yom Kippur, Passover, and Shabbat are described in the Bible as lasting "from evening to evening". The days are therefore figured locally.
  
  Halachically, the exact time when days begin or end is uncertain: this time could be either sundown (shekiah) or else nightfall (tzait ha'kochavim, "when the stars appear"). The time between sundown and nightfall (bein hashmashot) is of uncertain status. Thus (for example) observance of Shabbat begins before sundown on Friday and ends after nightfall on Saturday, to be sure that Shabbat is not violated no matter when the transition between days occurs.
  
  Instead of the International Date Line convention, there are varying opinions as to where the day changes. (See International date line in Judaism.)