Mo'ed Katan

Mo'ed Katan or Mo'ed Qatan is the eleventh tractate of Seder Moed of the Mishnah and the Talmud. It discusses the Halakha governing the days between the first and last days of Passover and Sukkot, known as Chol HaMoed. The tractate also covers the laws of aveilut. It has only three chapters and includes Gemara from both the Babylonian and Jerusalem Talmuds.

Summary

In the Babylonian Talmud:

Chapters 1 and 2 deal with Chol HaMoed.
Chapter 3 deals primarily with the laws of mourning and rabbinical censure, and gives accounts of the deaths of some of the Amoraim, including Rav Huna.

Permitted Activities on Chol HaMoed

The Mishnah Berurah by Rabbi Yisrael Meir Kagan summarizes the important principles that emerged from Mo'ed Katan. In Mishnah Berurah 530:1, he lists the activities permitted on Chol HaMoed:Davar Ha'Aved —One may do work in order to avoid a loss ;Tzarchei Moed—Even work that requires skill may be done if it is necessary for the purpose of eating on the festival. For other activities, only work that does not require skill may be done ;Bishvil Poel She'Ayn Lo Ma Yochal—If a person cannot afford to eat, it is permitted for them to work;Tzarchei Rabbim—Activities done for the benefit of the public may be done during Chol HaMoed;Ma'aseh Hedyot—Unskilled work.