A LAN hardware supplies networking capability to a group of computers
in close proximity to each other such as in an office building, a school,
or a home. LANs are useful for sharing files, providing access to printers
and access to the Net (among other things).
Most LANs are built with relatively inexpensive hardware such as Ethernet
cable and network interface cards (although wireless and other options
exist). Specialized operating system software is also often used to
configure a LAN. For example, some flavors of Microsoft Windows --
including Windows 98 SE, Windows 2000, and Windows ME -- come with a
package called Internet Connection Sharing (ICS) that support controlled
access to resources on the network.
A network adapter interfaces a computer to a network. The
term was popularized originally by Ethernet add-in cards for PCs.
Nowadays, most people use "network adapter" in a broader sense to include
PCMCIA devices (also know as credit card or PC Card adapters) and
analogous wireless devices.
Some network adapters are software packages that simulate the functions
of a network card. These so-called virtual adapters are especially common
in virtual private networking (VPN).