Tractate Eruvin

The Masechet Eiruvin deals in ten chapters with the laws of the eirouvin.
The Eiruvin gemara is the study of devices devised by rabbis to circumvent their own measures (but not those of the Bible) in order to safeguard the observance of Shabbat. The laws of Shabbos regarding the prohibition to take an object out of one domain to another, prohibit it from moving away from the city more than 2000 cubits. The various devices that allow transport from one dwelling to another, an action prohibited by the Sages.
The Eirouvin tractate is part of the Seder Moed.