A local area network (LAN) is a computer network that interconnects computers in a limited area, covering a small geographical area of 1-5 km, such as a residence, school, laboratory, university campus, or office building.
Ethernet and Wi-Fi are two of the most commonly used technologies in LANs. Some of the most common LAN protocols are Ethernet, Token Ring, and Optical Distributed Data Interface, or FDDI, while most wireless protocols in use today are 802.11a, 802.11b, 802.11g, and 802.11n.
What is MAN
A metropolitan area network (MAN) is a computer network that is larger than a single building local area network (LAN) but located in a single geographic area that is smaller than a wide area network (WAN). Typically, it is several LANs interconnected through a dedicated backbone connection. It can also refer to the public network infrastructure of a municipality or region. Typically used in cities and other locations with a coverage range of 50-60 km. Simply put, a metropolitan area network (MAN) can be thought of as a group of one or more LAN networks connected together by a single cable. RS-232, X-25, Frame Relay, and ATM are common protocols for MAN communication.
What is WAN
A wide area network (WAN) is a telecommunications network that extends over a large geographic area and is primarily used for computer networks. Wide area networks are typically established using leased telecommunications circuits. Approximately 100-1000 km in diameter, i.e. any network where communication links cross metropolitan, regional, or national borders. The devices involved are more diverse than those applied to other types of devices, from routers to switches, firewall modems, etc. Some of the most common WAN protocols in use today are Frame Relay, X-25, Integrated Services Digital Network, or ISDN, and Point-to-Point Protocol, or PPP.
From the preceding description, we may also know that the LAN covers the smallest distance, followed by the MAN, and then the WAN. Because a LAN contains the least number of network nodes, it is much easier to design and maintain than a MAN or WAN.