Jewish law says that Jews may not work on our Sabbath. One of the distinctive features of Judaism is that we get very specific about our terminology. One of the activities we define as “work” is carrying things outside of our houses or fenced yards. What things are we not allowed to carry around? Keys, purses, books, babies. In short almost anything.
This of course, makes it difficult for families with young children to get together on the Sabbath. So the rabbis decided that we could have a big “yard” that included many homes as long as it was properly enclosed and became one community