Street plan

A MAP was once a sheet of paper. The information it could impart—natural features, political boundaries, streets and railway lines—was limited by space and scale. Getting an update meant buying a new one. The modern map is almost a living thing. Its habitat is the personal computer or (increasingly) the smartphone. It can carry layer upon layer of data, from traffic conditions and public-transport routes to reviews of local restaurants and indoor plans of shops, museums and airports. And as the world changes, the map adapts.