Internet

What is the Internet?

The Internet, sometimes called simply "the Net," is a worldwide system of computer networks - a network of networks in which users at any one computer can, if they have permission, get information from any other computer (and sometimes talk directly to users at other computers). The U.S. Department of Defense laid the foundation of the Internet roughly 30 years ago with a network called ARPANET (Advance Research Project Agency Network). But the general public didn't use the Internet much until after the development of the World Wide Web in the early 1990s.

In 1957, the U.S. government formed the Advanced Research Projects Agency (ARPA), a segment of the Department of Defense charged with ensuring U.S. leadership in science and technology with military applications. In 1969, ARPA established ARPANET, the forerunner of the Internet.

ARPANET was a network that connected major computers at the University of California at Los Angeles, the University of California at Santa Barbara, Stanford Research Institute, and the University of Utah. Within a couple of years, several other educational and research institutions joined the network.

In response to the threat of nuclear attack, ARPANET was designed to allow continued communication if one or more sites were destroyed. Unlike today, when millions of people have access to the Internet from home, work, or their public library, ARPANET served only computer professionals, engineers, and scientists who knew their way around its complex workings.

What is the World Wide Web?

The World Wide Web came into being in 1991, thanks to developer Tim Berners-Lee and others at the European Laboratory for Particle Physics, also known as Conseil European pour la Recherche Nucleure (CERN). The CERN team created the protocol based on hypertext that makes it possible to connect content on the Web with hyperlinks. Berners-Lee now directs the World Wide Web Consortium (W3C), a group of industry and university representatives that oversees the standards of Web technology.

Early on, the Internet was limited to noncommercial uses because its backbone was provided largely by the National Science Foundation, the National Aeronautics and Space Administration, and the U.S. Department of Energy, and funding came from the government. But as independent networks began to spring up, users could access commercial Web sites without using the government-funded network. By the end of 1992, the first commercial online service provider, Delphi, offered full Internet access to its subscribers, and several other providers followed.

In June 1993, the Web boasted just 130 sites. By a year later, the number had risen to nearly 3,000. By April 1998, there were more than 2.2 million sites on the Web.

Today, the Internet is a public, cooperative, and self-sustaining facility accessible to hundreds of millions of people worldwide. Physically, the Internet uses a portion of the total resources of the currently existing public telecommunication networks.

The most widely used part of the Internet is the World Wide Web (often abbreviated "WWW" or called "the Web"). Its outstanding feature is hypertext, a method of instant cross-referencing. In most Web sites, certain words or phrases appear in text of a different color than the rest; often this text is also underlined. When you select one of these words or phrases, you will be transferred to the site or page that is relevant to this word or phrase. Sometimes there are buttons, images, or portions of images that are "clickable." If you move the pointer over a spot on a Web site and the pointer changes into a hand, this indicates that you can click and be transferred to another site.

To view files on the Web, you need Web browsing software. You use this software to view different locations on the Web, which are known as Web pages. A group of Web pages is a Web site. The first page of a Web site is often called the home page.

Just as each household in the world has a unique address, each Web page in the world has a unique Internet address, sometimes called a URL. For example, the Internet address of the Windows home page is http://www.microsoft.com/windows.

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Terms to Be Familiar With:

Browser--Contains the basic software you need in order to find, retrieve, view, and send information over the Internet.

Download--To copy data from a remote computer to a local computer.

Upload—To send data from a local computer to a remote computer.

E-mail - E-mail (electronic mail) is the exchange of computer-stored messages by telecommunication. E-mail can be distributed to lists of people as well as to individuals.  However, you can also send non-text files, such as graphic images and sound files, as attachments sent in binary streams.

Filter - Software that allows targeted sites to be blocked from view.  Example:  X-Stop, AOL@School

Home Page - The beginning "page" of any site.

HTML (HyperText Markup Language) - The coding language used to create documents for use on the World Wide Web.  There are three-letter suffixes used in coding that help to identify the type location one is viewing

HTTP (HyperText Transport Protocol) - the set of rules for exchanging files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. Relative to the TCP/IP suite of protocols (which are the basis for information exchange on the Internet), HTTP is an application protocol.

Hypertext - Generally any text that contains "links" to other text.

Search Engine - A web server that collects data from other web servers and puts it into a database (much like an index), it provides links to pages that contain the object of your search.

TCP/IP -- TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.

URL (Uniform Resource Locator) - The Internet address.  The prefix of a URL indicates which area of the Internet will be accessed.  URLs look differently depending on the Internet resource you are seeking.

WWW (World Wide Web) - A technical definition of the World Wide Web is: all the resources and users on the Internet that are using the Hypertext Transfer Protocol (HTTP).

What is a Web Browser?

A Web browser contains the basic software you need in order to find, retrieve, view, and send information over the Internet. This includes software that lets you:

▪         Send and receive electronic-mail (or e-mail) messages worldwide nearly instantaneously.

▪         Read messages from newsgroups (or forums) about thousands of topics in which users share information and opinions.

▪         Browse the World Wide Web (or Web) where you can find a rich variety of text, graphics, and interactive information.

The most popular browsers are Microsoft Internet Explorer and Netscape Navigator. The appearance of a particular Web site may vary slightly depending on the browser you use.

What is a URL?

Every server on the Internet has an IP number, a unique number consisting of 4 parts separated by dots. The IP number is the server's address.

165.113.245.2
128.143.22.55

However, it is harder for people to remember numbers than to remember word combinations. So, addresses are given "word-based" addresses called URLs. The URL and the IP number are one and the same.

The standard way to give the address of any resource on the Internet that is part of the World Wide Web (WWW). A URL looks like this:

http://www.matisse.net/seminars.html
telnet://well.sf.ca.us
gopher://gopher.ed.gov/

The URL is divided into sections:

transfer/transport protocol :// server (or domain). generic top level domain/path/filename

The first part of a URL defines the transport protocol. 

http:// (HyperText Transport Protocol) moves graphical, hypertext files
ftp:// (File Transfer Protocol) moves a file between 2 computers
gopher:// (Gopher client) moves text-based files
news: (News group reader) accesses a discussion group
telnet:// (Telnet client) allows remote login to another computer

Here's an example:

http://www.vrml.k12.la.us/tltc/mainmenu.htm

▪         http is the protocol

▪         www.vrml.k12.la.us is the server

▪         tltc/ is the path

▪         mainmenu.htm is the filename of the page on the site

1.      You do not have to enter http:// , most browsers will add that information when you press Enter or click the button at the end of the Address Bar.

2.      To view recently visited Web sites, click the down arrow at the end of the address field.

3.      When you start typing a frequently used Web address in the Address bar, a list of similar addresses appears that you can choose from. And if a Web-page address is wrong, Internet Explorer can search for similar addresses to try to find a match.

4.      The URL must be typed correctly.  If you get a “Server Does Not Have A DNS Entry” message, this message tells you that your browser can't locate the server (i.e. the computer that hosts the Web page). It could mean that the network is busy or that the server has been removed or taken down for maintenance. Check your spelling and try again later.

What are Domains?

Domains divide World Wide Web sites into categories based on the nature of their owner, and they form part of a site's address, or uniform resource locator (URL). Common top-level domains are:

.com—commercial enterprises	.mil—military site
.org—organization site (non-profits, etc.)	.int—organizations established by international treaty
.net—network	.biz—commercial and personal
.edu—educational site (universities, schools, etc.)	.info—commercial and personal
.gov—government organizations	.name—personal sites

Additional three-letter, four-letter, and longer top-level domains are frequently added. Each country linked to the Web has a two-letter top-level domain, for example .fr is France, .ie is Ireland.

 Searching the World Wide Web

When you do what is called "searching the Web," you are NOT searching it directly.  It is not possible to search the WWW directly.  The Web is the totality of the many web pages which reside on computers (called "servers") all over the world.  Your computer cannot find or go to them all directly.  What you are able to do through your computer is access one or more of many intermediate search tools available now. You search a search tool's database or collection of sites -- a relatively small subset of the entire World Wide Web. The search tool provides you with hypertext links with URLs to other pages. You click on these links, and retrieve documents, images, sound, and more from individual servers around the world.

There is no way for anyone to search the entire Web, and any search tool that claims that it offers it all to you is distorting the truth. 

How Do Search Engines Work?

Search Engines for the general web (like all those listed above) do not really search the World Wide Web directly. Each one searches a database of the full text of web pages selected from the billions of web pages out there residing on servers. When you search the web using a search engine, you are always searching a somewhat stale copy of the real web page. When you click on links provided in a search engine's search results, you retrieve from the server the current version of the page.