Chabad-Lubavitch is a chassidic movement founded by Rabbi Schneur Zalman of Liadi (1745-1812) in the White Russian town of Lubavitch. Chabad is an acronym for chochma (wisdom), binah (comprehension), and da'at (knowledge), the three intellectual facets needed to comprehend the ways of God.
Lubavitch outreach actually began with the activities of the sixth Lubavitch Rebbe, Rabbi Yosef Yitzchak Schneerson (1880-1950) to counter the anti-religious activities of the Soviets. When he passed away in 1950, in Brooklyn, N.Y., his son-in-law Rabbi Menachem Mendel Schneerson (1902-1994) led his chassidim in forming what would become the world's largest Jewish outreach effort. Chassidim were dispatched by the Rebbe (and, since his passing in 1994, by the Chabad organization) to the four corners of the world and everywhere in-between as sh'luchim (messengers), where they set up Chabad Houses to teach Jews about Judaism.
Innovative in their outreach techniques, Chabad is well known for their "Mitzvah Tanks" (redesigned RVs) and for standing on city streets asking strangers if they are Jewish and if they might want to put on tefillin (phylacteries) or light Shabbat candles. With over 2,700 institutions around the world, Chabad-Lubavitch is dedicated to offering every Jew the opportunity to make a Jewish connection.
Today, 3 Tammuz, is the yahrtzeit (anniversary of the death) of the last Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson, z”l.