Connect one computer to another and you have a network.
The Internet is a giant network of networks linking computers from all over the world. There are many kinds of networks, each defined by its communication protocol. On the Internet, computers can communicate across different platforms using a standardized addressing scheme.
To review the Internet and the services it offers, click this sidebar.
The basic elements of Internet communication are:
Internet Service Providers (ISPs)
Network Access Points (NAPs)
Making Internet Connections
The Internet is a giant computer network linking computers from all over the world.
For some users, the Internet is an infrastructure to access public and private networks. For other users, it is the essential bridge for the Web and email. The Internet comprises four essential parts:
The Internet supports a wide range of services that are available to users.
The basic Internet services are:
Electronic mail (email)
World Wide Web (the Web)
Mailing lists and newsgroups
File Transfer Protocol
Internet Service Provider
When you send a message over the Internet from your home, you contact your Internet Service Provider (using a dial-up modem or a cable modem). Your Internet Service Provider either sends your message directly to a Network Access Point, from where it is placed onto the Internet's backbone, or onto a shared line if the target site is relatively local. A Network Access Point (NAP) is like an airline hub, it's where regional ISP's connect to the Internet backbone. The lines between Network Access Points, called backbones, are super-fast.
Internet Service Providers
An Internet Service Provider, or ISP, is a company that has a connection to the Internet and provides Internet access to others (individuals, as well as companies), usually for a fee. Today there are thousands of ISPs throughout the world. Examples of ISPs in the U.S. are Netcom, AOL, and Earthlink.
ISPs pay a fee to connect to a regional network, which in turn connects to a national commercial backbone.
However, some larger ISPs connect directly to one of the commercial backbones. In the United States some major regional networks are BARRNet in California, NEARNET in Northeastern U.S., and CICnet in the Midwest.
Network Access Points (NAPs)
Regional networks are connected to Network Access Points, or NAPs. A NAP is a major interconnection point: the airline-like hub described earlier in this lesson. NAPs reduce network lengths, provide routing flexibility, and produce bandwidth savings. Many regional ISPs interconnect directly with each other using leased lines for regional connections that do not require access to a NAP. The connection between NAPs and between some regional networks (and major ISPs) and NAPs takes place over high-speed pathways, or superlinks, called backbones. The information traveling through backbones is managed by routers. Routers direct the information to the appropriate backbone according to its destination, thus ensuring that it gets to where it's supposed to go and is not lost on the way. Commercial backbone providers include PSINet, UUNet, ANS/AOL, and Sprint.
The following diagrams illustrates NAPs and backbones.
In the next lesson, URLs and their function as IP addresses will be discussed.