The Haftorah that we read on Shabbat has a long and interesting history.  It originates from the Rabbis’ response to the evil decree of Antiochus, the Greek king who ruled during the time of the Chanukah story. At that time, he decreed that it was forbidden to read the Torah publicly and he sent spies into the synagogues to enforce his decree under penalty of death. The Rabbis were very concerned that, under the circumstances, the Torah might be forgotten. They, therefore, established that each week, a specific portion from the Books of the Prophets, or Neviem, that had a similar theme as the parsha which was supposed to be read that week, would be read in place of the Torah reading.  In this way, the mitzvah of reading the Torah, which was established by Moshe Rabbeinu, himself, and reaffirmed by Ezra, could, at least in spirit, be preserved.  Fortunately, this response of the Rabbis did not concern Antiochus, who viewed the words of the Neviem as merely words of mussar and rebuke of the Jewish people.
    Originally, our Rabbis established that the Haftorah be read just as the Torah was read.  Each Haftorah was selected to contain a minimum of twenty-one pesukim or verses which allowed seven people to be called up for seven aliyot, each aliyah consisting of at least three pesukim. When the decree was rescinded and the Torah could be read publicly again, our Rabbis did not want to do away with this new practice. However, they did need to adjust the way it was performed so that it wouldn’t be confused with the Torah reading itself.
The problem was that they didn’t want to give the false impression that the Navi was on the same level as theTorah or that it should be accorded equal honor. This would have been a slight to the Torah which was God-given and was much older than the Navi.  Therefore, they established that only one person should read the entire Haftorah and that this person should first be called up to the Torah and read from it before beginning his recitation of the Haftorah.  This aliyah is called maftir and the one who is called up for it usually reads the last few pesukim of the Torah portion a second time.
    This custom of repeating the last few pesukim and the kaddish that precedes the maftir, is based on a very interesting argument in the Gemara. The Mishnah is the source that informs us of the number of aliyot we need to have when we read the Torah on any given day. Shabbat and Yom Tov mornings are the only times that we may add additional aliyot. On Shabbat we have a minimum of seven aliyot and on Yom Tov, five. There is a disagreement as to whether maftir is counted as one of the seven aliyot or not. We follow the opinion that it is one of the seven.  However, whenever it is feasible to accommodate the other opinion, that is what we do. Therefore, on Shabbat and Yom tov when there is a minimum requirement of Aliyot but adding is permitted, we do just that, we add the maftir. However, on Yom Kippur afternoon, Tisha B’Av, and all other fast days when we may only have three aliyot, we follow the main halacha and make the maftir the third aliyah. The Geonim who lived in the period after the Gemara established that kaddish should be said before the maftir in order to show that this is not one of the counted aliyot.
Another fascinating aspect of the maftir is that this is one of the only public services that a katan, a boy under bar mitzvah age, may lead. Not only can the boy recite the brachot on both his aliyah and the Haftorah, but he may also actually read the maftir from the Torah itself. This is because, as we mentioned before, by this time the congregation has already fulfilled its obligation of reading the entire Torah portion for that week and the verses of the maftir are merely a repetition of the last few verses that have already been read.
    From the time that the books of the Neviem were written they were transmitted to Bnei Yisrael in scrolls, written on parchment and having the appearance of miniature Sifrei Torah. Every shul had a multi-scroll set that included all the Neviem and the Haftorah was then read from the appropriate Navi scroll. If a person could not read the Haftorah from the scroll, then he would make the brachot and the b’al korei would read it for him. Although this is the practice in some shuls nowadays, most do not own the Sifrei Neviem in scrolls.
     There is disagreement among halachic authorities as to the proper procedure that should be followed if a shul does not own the Sifrei Neviem in scrolls. The Mishnah Berurah and others write that in this event the Haftorah should, at least, be read from a Tanach or from some other book that contains the whole Navi and not from a source that just contains the Haftorah portion by itself. They rule that the practice of reciting the Haftorah from a “Haftorah book” or from the Haftorah printed in the back of the Chumash is not a correct one and should be avoided. Indeed, in order to accommodate this opinion and make this easier for people, there are many publishers who print a Tanach with clear markings to show where the different Haftorot begin and end. On the other hand, there are others who disagree and rule that the Haftorah may be read from a “Haftorah book” and that there is nothing wrong with this.  There are certainly many shuls that fully rely on this opinion. It’s important to note that whichever way you hold, both opinions agree that if the Haftorah is not being read from a scroll, then each person should read the Haftorah quietly to themselves.
    As we’ve seen, there’s a lot more to the humble Haftorah than one might have imagined.  As with many practices in Judaism, opinions vary as to how best to perform them.  In all such matters, it’s always recommended that individuals consult their local halachic authority to learn how they should actually conduct themselves.