An eruv is a ritual halakhic enclosure made for the purpose of allowing activities which are normally prohibited on Shabbat, specifically: carrying objects from a private domain to a semi-public domain (carmelit), and transporting objects four cubits or more within a semi-public domain. The enclosure is found within some Jewish communities, especially Orthodox ones.

Shabbat or the Sabbath, also called Shabbos by Ashkenazim, is Judaism's day of rest on the seventh day of the week—i.e., Saturday. On this day, religious Jews remember the biblical stories describing the creation of the heaven and earth in six days and the redemption from slavery and the Exodus from Egypt, and look forward to a future Messianic Age. Since the Jewish religious calendar counts days from sunset to sunset, Shabbat begins in the evening of what on the civil calendar is Friday.