Shabu'ot is the festival in which we celebrate the giving of our Tora and our appointment as the people of God.
It is celebrated for one day in Israel and for two days in the Diaspora. This year Shabu'ot starts after Shabbat ends. Outside Israel then, we have a continuum of three holy days (qodesh): 1 shabbat, and 2 days of Yom Tob.
Yom Tob is very similar to Shabbat. We don't work and we refrain from doing all the activities we don't do on Shabbat, with basically one exception: okhel nefesh, i.e., those activities that were deem necessary for preparing food. Therefore, in Yom Tob we are allowed to cook and even to light a fire, but from an already lit fire, not from a match or from an electrical lighter. That is why it is customary to leave a lit candle at home, in case we need to light a fire for cooking or warming food. Another difference between Shabbat and Yom Tob is that on Yom Tob we can carry permitted (=non-Muktze) objects (foods, a Siddur, keys, etc.) in public areas even when there is no Erub in that area.
Since Shabbat ends as Shabu'ot begins, what do we do with the Habdala when Shabbat is over?
On the first night of Shabu'ot, Saturday night, we perform a special Habdala. We recite bore me-ore ha-esh, while looking at a lit candle, for the enjoyment of light and then, beforeShehecheyanu, we recite hamabdil, i.e., that haShem instructed us to distinguish between holy times and common times. But in this case, because Shabu'ot is also a holy time, we add and conclude this blessing saying hamabdil ben qodesh leqodesh, that HaShem made also a distinction between the holiness of Shabbat and the holiness of Yom Tob. Monday night we do a second Habdala as usual.
Shabbat Shalom and Chag Sameach!!!
for times of hadalakat nerot Shabbat and Yom Tob, end of Yom Tob, times of prayers, the Tikun of Shabuot night and the Las Vegas Mashadi Minyanim for those who travel to the Jewelry show, etc, etc.