"speech") consisted of the Rebbe's original thoughts on a wide variety of subjects, ranging from the weekly reading of the Torah to current important events.
The Talmud records that a heavenly voice once proclaimed that the opinions of the schools of Hillel and Shammai are both divrei Elokim chayim: “words of the living G‑d” (Eruvin 13b).
[1] Chabad Maamarim, especially the more well-known ones, are also usually named after their opening quotation from Scripture, whereas Sichot are generally referenced by the occasion (i.e. day of week, torah portion, or special event) on which they were delivered.
The manner of delivery also differed from that of a Sicha in three ways: Besides quotations from other areas of Torah, Maamorim were delivered exclusively in Yiddish; they were sung, not spoken, using the sing-song chant customarily used while studying Talmud; the Rebbe's eyes were closed throughout the Maamar.
In Chabad, when a boy (this custom is not followed by women) approaches his Bar-Mitzvah and/or wedding, it is customary for him to learn a Maamar dealing with topics relevant to the idea of Bar Mitzvah and marriage (respectively).
The maamar Be'Etzem Hayom Hazeh, from Torah Or by the Alter Rebbe, is recited at a Bris Milah, the Jewish circumcision ritual, by the father of the infant.
In length, they span anywhere from 5 to 144 discourses, which took anywhere between a few weeks to almost four years to recite and/or write.The most well-known of these are the Hemshechim Samech Vov, Te'erav and Ranat of Rabbi Sholom Dovber Schneersohn.