A computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a wide-area network (WAN). There are many different types of LANs Ethernets being the most common for PCs. 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.
10BaseT standard: (also called Twisted Pair Ethernet) uses a twisted-pair cable with maximum lengths of 100 meters. A star topology is common with 12 or more computers connected directly to a hub or concentrator. The 10Base-T system operates at 10 Mbps and uses baseband transmission methods.
100BaseT standard: A networking standard that supports data transfer rates up to 100 Mbps (100 megabits per second). 100BASE-T is based on the older Ethernet standard. Because it is 10 times faster than Ethernet, it is often referred to as Fast Ethernet.