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Every computer that is connected
to the Internet is part of a network, even the one in your home. For example,
you may use a modem and dial a local number to connect to an Internet Service
Provider (ISP). At work, you may be part of a local area network (LAN), but you
most likely still connect to the Internet using an ISP that your company has
contracted with. When you connect to your ISP, you become part of their
network. The ISP may then connect to a larger network and become part of their
network. The Internet is simply a network of networks. Most large communications
companies have their own dedicated backbones connecting various regions. In
each region, the company has a Point of Presence (POP). The POP is a place for
local users to access the company’s network, often through a local phone number
or dedicated line. The amazing thing here is that there is no overall
controlling network. Instead, there are several high-level networks connecting
to each other through Network Access Points or NAPs.
