A computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings, and connect workstations and personal computers. Each individual computer or node in a LAN has its own central processing unit with which it executes programs, but it is also able to access shared data and devices anywhere on the network. Users can also use the LAN for electronic mail. There are many different types of LANs; ethernet is the most common for personal computers. LANs are capable of transmitting data at very fast rates, much faster than data can be transmitted over a telephone line; but the distances are limited, and there is also a limit on the number of computers that can be attached to a single LAN.