A local area network (LAN) connects a set of computers so that they can communicate with one another directly. Once upon a time, the term local was quite appropriate—early LANs spanned a limited space. A LAN typically connected systems located within a single room or in an area confined within one story of a building.
Gradually, LANs snaked across multiple floors of a building. As time went by, new technologies made it possible for a LAN to span a campus consisting of several buildings, or even to incorporate sites located at great distances from one another.