Chabad, also known as Lubavitch, Habad and Chabad-Lubavitch (Hebrew: חב"ד לובביץ; Yiddish: חב״ד ליובוויטש), is an Orthodox Jewish Hasidic dynasty. Chabad is one of the world's best-known Hasidic movements, particularly for its outreach activities. It is one of the largest Hasidic groups and Jewish religious organizations in the world. Unlike most Haredi groups, which are self-segregating, Chabad operates mainly in the wider world and caters to secularized Jews.

Founded in 1775 by Rabbi Shneur Zalman of Liadi, the name "Chabad" (חב״ד‎) is an acronym formed from three Hebrew words—Chokhmah, Binah, Da'at (the first three sefirot of the kabbalistic Tree of Life) (חכמה, בינה, דעת‎): "Wisdom, Understanding, and Knowledge"—which represent the intellectual and kabbalistic underpinnings of the movement. The name Lubavitch derives from the town in which the now-dominant line of leaders resided from 1813 to 1915. Other, non-Lubavitch scions of Chabad either disappeared or merged into the Lubavitch line. In the 1930s, the sixth Rebbe of Chabad, Rabbi Yosef Yitzchak Schneersohn, moved the center of the Chabad movement from Russia to Poland. After the outbreak of World War II, he moved the center of the movement to the United States.

In 1951, Rabbi Menachem Mendel Schneerson formally accepted the leadership as the seventh Chabad Rebbe. He transformed the movement into one of the most widespread Jewish movements in the world today. Under his leadership, Chabad established a large network of institutions that seek to satisfy religious, social and humanitarian needs across the world. Chabad institutions provide outreach to unaffiliated Jews and humanitarian aid, as well as religious, cultural and educational activities. Prior to his death in 1994, Schneerson was believed by some of his followers to be the Messiah, with his own position on the matter debated among scholars. Messianic ideology in Chabad sparked controversy in various Jewish communities and is still an unresolved matter. Following his death, no successor was appointed as a new central leader.

In 2018, Marcin Wodziński estimated that the Chabad movement accounted for 13% of the global Hasidic population. The total number of Chabad households is estimated to be between 16,000 and 17,000. The number of those who sporadically or regularly attend Chabad events is far larger; in 2005 the Jerusalem Center for Public Affairs reported that up to one million Jews attend Chabad services at least once a year. In a 2020 study, the Pew Research Center found that 16% of American Jews attend Chabad services regularly or semi-regularly.