Για να το διβάσετε στα Ελληνικά, κάντε κλικ εδώ
Every Shabbat, after the reading of the Torah, we read the Haftarah. What is the Haftarah? It is (usually) an excerpt from the Prophets which is related to the portion of the Pentateuch that was read before. It is customary that the person reading the Haftarah also reads a few verses of the Torah. From the portion that was just completed. The reading of the Haftarah is not considered part of the 7 Aliyot of Shabbat, it is the 8th (to read more about the 7 Aliyot of the Torah, click here). This is what it is possible for a Kohen or a Levi to read the Haftarah.
There is no Haftarah during the readings of the Torah on Mondays and Thursdays. Besides for Shabbat, we read a Haftarah on special days such as Rosh Chodesh, fast days etc. In these cases, when we have only 3 Aliyot, the third person coming up to the Torah is the one who will read the Haftarah. It will be an Israelite, not a Kohen or Levi.
Why do we read the Haftarah?
Many years ago (2nd century BCE), one king decreed that the Jews could not read the Torah. The Sages of this time instituted to read (instead of the Torah which was forbidden) an excerpt from the Prophets corresponding to the Portion of the week. In this way, they kept the reading even during the period when it was banned. This continued even after the decree was canceled and this is how we read the Haftarah after the reading of the Torah.
Shabbat Shalom,
Arie from the Yeshiva