During the week, most of us travel, moving from place to place, for work or other purposes. This stems from a basic human deficiency: when we remain stationary, we cannot make a living or meet our needs. To do so, we are forced to travel and leave our home base. Shabbat is meant to give us a break from worry and hassle, so we can contemplate the inner perfection of creation, delighting in God and His goodness.
Therefore, even people not carrying anything, may not go beyond teĥum Shabbat, a distance in each direction of one mil (2,000 amot, 912 meters, or .57 miles). Those spending Shabbat anywhere other than a city or town may walk only one mil in each direction. In a city or town, the entire settled area is considered one place, so someone spending Shabbat there may walk up to one mil beyond the city limits. Someone whose flight was delayed so much that the plane landed after Shabbat began, may walk up to a mil outside of the airport. Since it can be assumed that airports are enclosed, the entire airport is considered to be one place.
