The Eruv עירוב

An eruv is a ritual halachic enclosure that allows Orthodox Jews to carry objects outdoors on Shabbos, normally forbidden. With an eruv one can carry keys, tissues, medication and babies, and use strollers and canes. Eruvin are typically formed with wires on poles together with walls and natural boundaries, and are checked every week; communities announce before Shabbos whether the eruv is up.