Internet/World Wide Web Concepts

1) The Internet is a network of networks connected using TCP/IP.

2) The World Wide Web is comprised of Internet resources that use HTTP.

3) Web pages are located by their URLs.

4) Domain names (.com, .edu, .gov, etc.) indicate something about a page's origin.

5) Web pages are created using HTML.

6) Browsers allow you to interact with Web pages.

1) The Internet is a network of networks connected using TCP/IP.

The Internet is the vast global network of networks which use Transmission Control Protocol/Internet Protocol (TCP/IP). TCP/IP is a suite of protocols, or several sets of rules, that govern communication between the networks that make up the Internet.

E-mail, telnet, gopher, chat, and the World Wide Web are examples of Internet services.

Some History:
The Internet evolved from the ARPANet (Advanced Research Projects Agency Network) which was created in 1969 by the U.S. Department of Defense and utilized Network Control Protocol (NCP).

Developed and implemented on many networks in the 1970s, TCP/IP officially replaced NCP on the ARPANet in 1983. (At the same time, MILNET, the military segment of the network, was split off from ARPANet.)

In the 1986, the US National Science Foundation launched NSFNet which became much of the backbone for what we know today as the Internet. By 1989/90, ARPANet formally ceased to exist and the Internet had become a huge international network.

2) The World Wide Web is comprised of Internet resources that use HTTP.

The World Wide Web is comprised of those Internet resources that use Hypertext Transfer Protocol (HTTP). Although often used interchangeably, the terms the Net and the Web do not really refer to the same thing. The Web is part of the Net, but there are plenty of resources on the Net which are not on the Web ( i.e. do not use HTTP).

Hypertext Transfer Protocol provides rules for exchanging text, graphic, audio, video, and multimedia files. HTTP allows text and multimedia elements from various locations to be easily linked. Just click and you are there (theoretically anyway).

Some History:
Hypertext Transfer Protocol was developed in 1990 by Tim Berners-Lee of CERN (European Organization for Nuclear Research) and released the following year.

3) Web pages are located by their URLs.

A Uniform Resource Locator (URL) indicates the location of a particular Internet resource or file. When we refer to a page's Web Address, we are referring to its URL. For instance the URL or Web address of this page is:

In technical terms, each resource on the Internet is actually identified by its IP (Internet Protocol) Address: a 32-bit numerical address consisting of four numbers, each of which can range from 0 to 255. For instance, 3.197.13.210 could be an IP Address. (The current IP system, IP.v4, is gradually being replaced with a system that allows many more addresses, the 128-bit IP.v6.)

When you use a URL to locate a Web page, its domain name (see below) is actually translated into an IP Address by the Domain Name System (DNS), introduced in 1984. A domain name uses words and abbreviations instead of long strings of numbers and is thus easier to remember.

In addition to the domain name, the URL also indicates the hierarchical directory structure in which the particular file resides, the name of the file and the kind of file it is.

The basic structure of a Web page's URL is:

Protocol

Domain Name

Path

File

Let's take another look at the URL for the page you are looking at right now:

Here are the four main sections:

Protocol	Domain Name	Path	File
http://	hudson2.skidmore.edu	irc/library/research/help/	internetconcepts.htm

Protocol:
Since what you are looking at right now is a Web page, it uses Hypertext Transfer Protocol (http://). http://hudson2.skidmore.edu/irc/library/research/help/internetconcepts.htm
[See #2 above.]
(For non-Web resources this might be File Transfer Protocol (ftp://) or Telnet (telnet://) or another protocol.)

Domain Name:
A typical Domain Name consists of three main pieces on information:

Host Server:

This is the particular server (computer) on which the file is located. By custom, HTTP servers are named WWW. This page is on the WWW server at Skidmore:
http://www.skidmore.edu/irc/library/research/help/internetconcepts.htm

Calling HTTP servers WWW is custom only however. For instance the server on which job opportunities here at Skidmore are posted is called "Apollo."
http://apollo.skidmore.edu:1111/hr/hr.hr_jobs.disp_jobs

Second-level Domain Name:

This is the name of the organization, institution, company etc.
which has registered for the IP Address (see above).
http://www.skidmore.edu/irc/library/research/help/internetconcepts.htm

Lower-level domain names are possible. For instance, if technical configurations at Skidmore were different, the library could be a third-level domain. The library home page would then be http://www.library.skidmore.edu.

Top-level Domain Name:

Indicates the type of organization which has registered for a specific IP Address or the country of origin. Since Skidmore College is an educational institution all pages on its server use the suffix ".edu". (For more about Top Level Domain names, see #4 below.)
http://www.skidmore.edu/irc/library/research/help/internetconcepts.htm

Path:
The path indicates the directory or series of directories which house the file. These directories are "nested," they sit one within the other. The file internetconcepts.htm is in the help directory which is in the research directory which is in the library directory which is in the irc directory (which is on Skidmore's HTTP server, www).
http://hudson2.skidmore.edu/irc/library/research/help/internetconcepts.htm

File:
The file has two parts: the first indicates the file's name (in this case internetconcepts) and the second indicates the type of file (in this case .htm). Since this is a web page the file type is Hypertext Markup Language (abbreviated .htm or .html for files), the coding language for creating Web pages. [See #5 below.]

The file type does not have to be HTML however. Two common file types for graphics encountered on the World Wide Web are GIF (Graphics Interchange Format) and JPEG (Joint Photographic Experts Group).

The banner at the top of this page is a graphic file:

4) Domain names (.com, .edu, .gov, etc.) indicate something about a page's origin.

Domain names, sometimes referred to as top-level domain names (see above), indicate the type of organization or the country on whose server a web page resides.

Some familiar domain names are

.com	commercial	.net	network
.edu	education	.mil	military
.gov	(US) government	.uk	United Kingdom
.org	non-profit organization	.ca	Canada

In November 2000 several new domain names were approved:

.aero	air transport	.museum	museums
.biz	businesses	.name	individual/personal registrations
.coop	co-operative businesses	.pro	licensed professionals
.info	anyone/anything

The number and type of domains in use is increasing and changing and will likely continue to do so in the next few years.

Individuals or organizations can lease space on commercial servers and create Web pages with non-commercial content on their Web pages, so while domain names provide a clue about the type of organization that has registered the server, they do not always provide clues about the Web pages/sites on the server.

5) Web pages are created using HTML.

Web pages are created using Hypertext Markup Language (HTML), a series of codes that defines the format and structure of documents on the World Wide Web (see #2 above).

In Explorer, you can look at a page's coding by going to View and selecting Source.

6) Browsers allow you to interact with Web pages.

Web browers allow you to request specific files via HTTP; they allow you to look at Web pages. Netscape, Explorer and Opera are all graphical browsers; they allow you to look at images as well as text. Lynx is an example of a text-only browser.

Some History:
The first graphical browser, Mosaic, was invented in 1992 by Marc Andreessen at NCSA (the National Center for Supercomputing Applications). Andreessen later went on to develop Netscape.

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