A local area network (LAN) is a private network that connects computers in a single location, such as a private home or office building. Establishing a LAN allows LAN users to share files, software, and devices such as printers and fax machines. The Internet, on the other hand, is a public, global wide area network (WAN) that connects millions of smaller networks, with more than a billion computers connected at any given time. The most basic difference between a LAN and the Internet, then, is that a LAN is private and localized, while the Internet is public and global.
An Ethernet cable, which can be used to connect a computer to a router.
A LAN can facilitate the sharing of files and resources by connecting computers through a central device known as a router. The router acts as an intermediary, directing data traffic on the LAN. Computers can be connected to a router using an Ethernet cable, or a router can communicate wirelessly using radio waves.
An ADSL modem, one of the ways to connect to the Internet.
The Internet connects millions of networks through T1 telephone lines, fiber optic cable, and other technologies. A common aspect between a LAN and the Internet is that they both use routers to route traffic. Internet routers direct traffic across the Internet and a LAN router directs traffic on the LAN.
A router can be used to connect a LAN to the Internet.
Internet access is an option that can be integrated into a LAN if desired. A central modem is attached to or built into the router, providing a gateway between the LAN and the Internet. A firewall is normally present at the gateway to act as a one-way valve, preventing unwanted public traffic from accessing the LAN. The firewall only allows the flow of data that has been specifically requested from the computers on the LAN.
Local area networks are often used in offices.
Somewhat paradoxically, there are situations where a LAN is set up for the sole purpose of providing Internet access. This is useful for families who have two or more computers but only want to share an Internet account and nothing else. It is easy to see how using a LAN for this purpose can lead to the incorrect assumption that a LAN and the Internet are the same thing.
LANs consist of two or more computers connected to each other.
Municipalities that offer free public access to wireless Internet do so through a LAN, technically known as a Municipal Area Network (MAN). A Campus Area Network (CAN) is a LAN that has been extended to cover the campus grounds and typically provides local resources along with Internet access. These larger networks are variations of the LAN, although they are still localized.
Fax machines can be shared among all users on the same LAN.
Exposing a LAN to the Internet creates security risks. Hackers may find a way around firewalls, and LAN users may unknowingly download files containing viruses, Trojans, spybots, keyloggers, or other malicious programs. Once a single computer on a LAN is infected, the infection can quickly spread throughout the LAN. Internet access can also serve as a distraction for employees who don’t need it.
Network cable testers are frequently used to troubleshoot problems with a LAN connection.
Because a LAN is often used as a gateway to the Internet, it’s easy to think of a LAN and the Internet as synonyms. However, a LAN does not require Internet access, and its sole purpose may be to easily transfer files between computers that are relatively close to each other, or to share printers, fax machines, or other hardware.
Acoustic couplers, which send and receive computer data over telephone lines, preceded modern modem technology in the early days of Internet use.
