During these days, we try to implement any type of joyous activity that is permissible. We therefore make siyumim, which give us reason to rejoice. Through this, we reveal the inner good hidden within the sadness.
-Sefer Hasichos 5751 vol. 2, p. 708
It is especially appropriate to arrange siyumim with as many people as possible, including children and those who may not have completed the tractate themselves. The Rebbe encouraged making siyumim on tractates that are easy to explain and complete quickly, such as Maseches Tamid (the shortest tractate, only eight pages), whose conclusion is "the song the Levites would sing in the Beis Hamikdash." Also, the siyum of "Kol Banecha Limudei Hashem"—in the four tractates: Berachos, Nazir, Yevamos, Kerisos—acronym "Banecha"—these siyumim can include even a Jew you meet in the street or in the middle of his business, by repeating the conclusion before him, or even just saying the concluding statement without telling him it is a siyum, since "one may benefit a person even in his absence."
The Rebbe also encouraged arranging siyumim even on Erev Tisha B’Av and Tisha B’Av itself, in a manner permitted by Shulchan Aruch, and to make a siyum on the Shabbos during the Nine Days. It is especially important this year to arrange siyumim "with a multitude of people is the King’s glory," to unite many Jews in the joy of completing Torah, including children (not only those lacking knowledge, but also those young in years) who are not yet capable of understanding, similar to the custom on Erev Pesach to bring even the youngest children.
It is customary to conclude every siyum with a suggestion to give tzedakah, in addition to concluding with words of Ahavas Yisrael (love of a fellow Jew).
Although there are opinions that a siyum can be made on a chapter or a complete tractate of Mishnayos, it is preferable to make a siyum on a tractate of Gemara, a "siyum" with all the details, according to all opinions, such as Maseches Tamid. In Lubavitch, at a siyum on a tractate, only "Hadran alach" and the names of the sons of Rav Papa were recited, followed by the regular Kaddish D'Rabbanan. There is a discussion regarding which Kaddish to recite, but the common practice is to recite the regular Kaddish D'Rabbanan.
