They have trained and ordained thousands of rabbis, educators, ritual slaughterers, and ritual circumcisers, who are all accompanied by equally motivated spouses and typically large families, all of whom aim to fulfill their mandate of Jewish outreach, education, and revival. They look for and recruit people who want to join them, and they are the originators of, and major players in, the Teshuva movement, which encourages Jews alienated from their religion to become more Jewishly aware and religiously observant.

Rabbi Menachem Mendel Schneerson greatly emphasized spreading awareness of the coming of Moshiach, the Jewish Messiah, and preparing for his imminent arrival. Belief in the imminent coming of Moshiach is a fundamental Jewish belief. The Era of Redemption, or Geula, is the culmination of the spiritual work since the Creation of the world. We prepare and pave the way for Moshiach's coming by doing Mitzvoth - the 613 commandments for Jews, as detailed in the Torah. Non-Jews have 7, G-d given, Noahide Laws and the Rebbe strongly encouraged raising awareness of these Laws.

Once, when asked what remains to be done to bring Moshiach, the Rebbe answered that we need to perform "Acts of Goodness and Kindness," now a popular catchphrase. Rabbi Schneerson intended that Moshiach awareness be an essential part of everything we do, and thus it is unusual for any Chabad function to be without mention of the desire for the immediate Redemption.

The worldwide headquarters of the Chabad movement is 770 Eastern Parkway in Brooklyn, in the neighborhood of Crown Heights.

This movement attaches importance to singing Hasidic tunes, either with or without words. Some of these can be found in Midi format here (http://www.geocities.com/novartza/Main/Midis.htm) .

Rabbi Schneerson's passing in 1994 has created a rift of sorts among Chabad followers, and between Chabad and other Jews. Many of the his teachings were interpreted to mean that he was the destined Messiah, though no Rabbinic authorities outside of Chabad accepted this as fact. After his passing, some Chabad authorities held that he could not be the Messiah, while others claimed that according to Jewish belief, the Messiah could come from the living or the dead, while others debated whether the classic meaning of death could apply at all to the truly righteous, and a small number even claimed that Schneerson was an incarnation of God. The thought that the a person could be an incarnation of God, or that the Messiah could come from the dead, has provoked some strong reactions; a work by Dr. David Berger, professor of history at the City College of New York, enumerated criticisms of these views.

Origins
Chabad traces its roots back to the beginnings of Hasidic Judaism:

Rabbi Israel ben Eliezer 1698 - 1760 was known as the Baal Shem Tov (abbreviated as BeSHT, meaning "Master of the Good Name") a title rarely applied, and only in exceptional circumstances to a known Jewish holy man and miracle worker beloved and revered by the common folk. According to Hasidic tradition, he studied the inner secrets of the Torah under the legendary Biblical figure Achiah the Shilonite, who the Talmud identifies as never having died. He based his nascent movement in Mezibush, Ukraine.
Rabbi Dovber of Mezeritch d. 1772. Sought out the Baal Shem Tov and became his leading disciple. He was well-versed in the Lurianic Kabbalah and when he met the Baal Shem Tov he acknowledged him as his master in this area of esoteric mystical wisdom. Upon the death of the BeSHT he assumed the leadership of the movement that would become known as Hasidism .
Rebbes of Chabad:

Rabbi Shneur Zalman of Liadi 1745 - 1812, son of Rabbi Boruch.
Rabbi Dovber 1773 - 1827, son of Shneur Zalman.
Rabbi Menachem Mendel 1789 - 1866, grandson of Shneur Zalman and son-in-law of Dovber.
Rabbi Shmuel 1834 - 1882, son of Rabbi Menachem Mendel .
Rabbi Sholom Dovber 1860 - 1920, son of Rabbi Shmuel.
Rabbi Joseph Isaac Schneersohn 1880 - 1950, only son of Sholom Dovber.
Rabbi Menachem Mendel Schneerson 1902 - 1994, sixth in paternal line from Rabbi Menachem Mendel, and son-in-law of Joseph Isaac.
The names "Schneersohn" and "Schneerson" began as patronymics by Shneur Zalman's descendants. The first form of this name was "Shneuri" (Hebrew for "of Shneur".) This was later changed to "Schneerson".