39 Melakhot

The 39 Melakhot (Hebrew: ל״ט אבות מלאכה, lamed-tet avot melakhah, "39 categories of work") are thirty-nine categories of activity which Jewish law identifies as prohibited by biblical law on Shabbat. These activities are also prohibited on the Jewish holidays listed in the Torah ("Yom Tov"), but there are significant exceptions that permit carrying and preparing food under specific circumstances on holidays (except Yom Kippur).

In addition to the 39 melakhot, certain other activities are forbidden on Shabbat due to rabbinic law.

There are often disagreements between Orthodox Jews and Conservative Jews or other non-Orthodox Jews as to the practical observance of Shabbat. It is of note that the (strict) observance of Shabbat is often seen as a benchmark for orthodoxy and indeed has legal bearing on the way a Jew is seen by an Orthodox religious court regarding their affiliation to Judaism.