A LAN is a private network connecting computers in one location, allowing file and resource sharing through a router. The Internet is a public WAN connecting millions of networks. A firewall protects LANs from unwanted public traffic, and LANs can provide access to the Internet. Larger networks like MANs and CANs are variations of LANs. Exposing a LAN to the Internet creates security risks, and a LAN can be used without Internet access.
A local area network (LAN) is a private network that connects computers in one location, such as a private residence or office building. Creating a LAN allows you to share files, software, and devices such as printers and fax machines among users on the LAN. The Internet, by contrast, is a public, global Wide Area Network (WAN) that connects millions of smaller networks with over a billion computers connected at any given time. The key difference between a LAN and the Internet, then, is that a LAN is private and localized, while the Internet is public and worldwide.
A LAN can facilitate the sharing of files and resources by connecting computers to each other 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.
The Internet connects millions of networks through T1 phone lines, fiber optic cables and other technologies. A common feature between a LAN and the Internet is that they both use routers to route traffic. Internet routers direct traffic to the Internet and a LAN router directs traffic to the LAN.
Internet access is an option that can be incorporated into a LAN if desired. A central modem is attached to or integrated into the router, providing a gateway between the LAN and the Internet. A firewall is typically present in the gateway to act as a one-way valve, preventing unwanted public traffic from entering the LAN. The firewall only allows the flow of data that has been specifically requested by computers on the LAN.
Somewhat paradoxically, there are situations where a LAN is set up for the sole purpose of providing access to the Internet. This is useful for families who have two or more computers but just want to share an Internet account and nothing more. It’s easy to see how using a LAN for this purpose could lead to the erroneous assumption that a LAN and the Internet are one and the same.
Municipalities that provide free, wireless public access to the 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 campus grounds, commonly providing local resources along with Internet access. These larger networks are variations on the LAN, albeit still localized.
Exposing a LAN to the Internet creates security risks. Hackers may find a way around firewalls, and users on the LAN may unknowingly download files that contain viruses, trojans, spybots, keyloggers, or other malicious programs. Once a single computer on a LAN becomes infected, the infection can travel rapidly across the entire LAN. Internet access could also act as a distraction for employees who don’t need it.
Because a LAN is often used as a gateway to the Internet, it’s easy to think of LAN and the Internet as synonyms. However, a LAN does not require Internet access, and its only purpose may be to easily transfer files between computers that are in close, relative proximity to each other, or to share printers, fax machines, or other hardware.
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