A Brief History of the Internet-- Basic Concepts and terms of Internet

Brief  History of Internet

Internet, a global network that connects other computer networks, together with software and protocols for controlling the movement of data. The Internet, often referred to as 'the Net', stems from a network called ARAPNET (Advanced Research Project Agency Network), which was initiated in 1969 by a group of universities and private research groups funded by the US Department of Defense. It now covers almost every country in the world. Its organization is informal and deliberately nonpolitical--its controllers tend to concentrate on technical aspects rather than on administrative control.

Introduction to the Internet

The connection of computers can form a network, this connection may be direct (by direct cabling) or indirect (dial-up). The benefit of connecting computers can exchange information and share resources such as application software, printers, files, databases or even other networks

The interconnection of networks among the world forms a dynamic international network system, which a group of computers, paths or networks may suddenly disappear or appear. However, different networks may use different transmission methods or protocols, so a gateway should be needed in order to connect two different networks together.

The Resources in Internet

The Internet offers users a number of basic services including data transfer, electronic mail, and the ability to access information in remote databases. A notable feature is the existence of user groups, which allow people to exchange information and debate specific subjects of interest. In addition, there are a number of high-level services. For example, MBONE (multicast backbone service) allows the transmission of messages to more than one destination. It is used in videoconferencing.

The World Wide Web, known as 'the Web', is another high-level Internet service, developed in the 1990s at CERN in Geneva. It is a service for distributing multimedia information, including graphics, pictures, sounds, and video as well as text. A feature of the World Wide Web is that it allows links to other related documents elsewhere on the Internet. Documents for publication on the Web are presented in a form known as HTML (hypertext mark-up language). This allows a specification of the page layout and typography as it will appear on the screen. It also allows the inclusion of active links to other documents. Generally, these appear on the screen display as highlighted text or as additional icons. Typically, the user can use a mouse to 'click' on one of these points to load and view a related document. Many commercial and public organizations now have their own Web site (specified by an address code) and publish a 'home page', giving information about the organization.

Up to the mid-1990s, the major users of the Internet were academic and research organizations. This has begun to change rapidly with individual home users linking in through commercial access providers and with a growing interest by companies in using the Internet for publicity, sales, and as a medium for electronic publishing. At the same time, there are problems with the flow of information across national borders, bringing in debates about copyright protection, data protection, the publication of pornography, and ultimately political control and censorship.

Terminology

Internet

It could be said that the internet is the most valuable legacy left over from the Cold War. It originally came into being as the ARPANet, which was founded by the U.S. Defense Department‘s Advanced Research Projects Agency (ARPA) to link academic research centres involved in military research. Nowadays, Internet has grown far beyond its original conception.

An internet is a network of networks, a kind of meta-network. or a global network that connects other computer networks, together with software and protocols for controlling the movement of data. The Internet, often referred to as 'the Net', simply put, the internet is a set of protocols (rules) for transmitting and exchanging data between networks. In a broader sense, it is a worldwide and a repository of global information resources.

Transmission Control Protocol/Internet Protocol (TCP/IP)

It is a standard rule set for internet communication. The essence of the internet is not the wire, but the means for sending and receiving information across the wire. It doesn‘t matter what type of systems are connected to the internet. The important thing is that they all use the same protocol, TCP/IP, to communicate with each other.

TCP handles data integrity, and make sure that data gets to the destination without errors, while IP is the protocol that controls how data moves around on the internet.

Domain Name

Every internet server has a numerical IP (Internet Protocol) address, which usually consists of four numbers between 0 and 255 separated by periods (something like 185.35.117.0, for instance). Computers prefer numeric addresses of this type because they are precise. Unfortunately, humans have trouble remembering numbers, and prefer to use meaningful text addresses, like www.mysite.com. That ‘s what a domain name is: a text alternative to an IP address. You can use the two interchangeably. If you know the domain name, you don‘t have to know everything about the IP address.

Most servers have applied for and received a domain name from the Internet Network Information Centre, which handles domain name registrations. As long as your Web pages are located on server that has a domain name, you can use that domain name in the addresses for those Web pages.

Domain Name System

A domain name represents a hierarchy, starting with the most general word on the right and moving to the most specific on the left. It can include a country code, an organization code and a site name. For instance, myname.com.hk, reading from right to left, specific the name of a site in Hong Kong (“hk”) in the commercial (“com”) subcategory, called “myname”.

There are some country codes listed below

“au” for Australia

“ca” for Canada

“fr” for France

“nz” for New Zealand

“uk” for United States

There are some organisation codes listed below

“edu” for education

“gov” for government

“net” for network

“com” for commercial

“org” for organization

UNIX

It is an operating system which most Web pages reside on Unix servers. Unlike MS-DOS and Windows systems, Unix systems are case-sensistive file paths and file name. Therefore, if you see a path and file name, you should type exactly as it appears.

Web Page

A Web page is a hypertext (HTML) document contained in a single file. To have more than one Web page, you must have more than one file. Remember that a Web page can be any length, although most Web pages display no more than 2 or 3 screens of data

A Web page is simply a plain text document. All codes are entered into the document as ordinary text, with none of the binary-level formatting that a word processor would embed in. When you mark some text as italic, you have to do it by using italic tags in HTML. This cuts down on the computer overhead, allowing Web pages to remain small but still pack.

When a browser displays a Web page, the page may appear to contain special graphical elements like logos or buttons. These graphics don‘t reside in the HTML file, they are separate files that HTML file reference. For instance <IMG SRC=“mylogo.gif”>.

Web site

The term may have different meanings, some people may regard servers as Web sites, that is sites on the Web. However, it is more likely to refer to a collection of related and linked Web pages during a common theme or subject matter as a Web site. The address that can identify the Web page is the Web site address.

Hypertext

Hypertext is a linking that occurs within and between documents. The basic mechanism is the capability to embed a hypertext link, a kind of jump point that allows a viewer to jump from a place in a Web page to any other Web page.

Homepage

When you start your browser, it loads whatever Web page you designate as its homepage. Most browsers have a command that takes you back to the homepage, usually your ISP‘s homepage or some common Web browser homepage. Therefore, a homepage may serve as an entry point to a Web site, and generally keep small, often serving simply as menus or directories to other Web pages that make up the rest of the Web site. The idea is that a viewer need only display the homepage and then decide what else to view in the remainder of the Web site.

Internet Service Provider (ISP)

A company or organization provides you access to the Internet, and the service provider may also give you space for a personal or non-commercial Web site at little or no cost

Internet Site Addresses

Each page on the Internet has an address that identifies it. This address is used to locate the page. Internet addresses are called URLs, which stand for Uniform Resource Locators.

A URL has several parts:

The first part of an Internet address is the protocol type. A protocol is a set of rules used to exchange information between computers.

For example, the first part of a Web page address is http. It stands for Hypertext Transfer Protocol, the protocol used on the Web. If the first part of an FTP address is ftp, which stands for File Transfer Protocol. This type of site store files that users can download.

After the protocol type, the address contains a colon and two forward slashes, such as http:// or ftp://

Next is the address of the computer (server) on which the site is stored. The computer identifies the server on the network that contains the site.

For example, www.yahoo.com and www.microsoft.com are all computer addresses.

The domain type is the part of the computer address. This is the three-character extension at the end of the computer name. The domain type identifies the type of organization of the host computer.

For example, .com indicates a commercial or business organization, such as microsoft.com. The .edu extension identifies an educational facility such as umich.edu, the University of Michigan site.

A URL might also include a page name or address that identifies a specific page within a site. When you go from the home page of a site to a page within the site, the page address is added to the URL.

For example, the address of the home page for the Seattle Sidewalk site is http://seattle.sidewalk.com. If you click a hyperlink from home page to go to the movie page within the site, the URL for that page is http://seattle.sidewalk.com/movies.

The Web browser displays the address of the current page in the Status bar at the bottom of the screen and in the Address bar.

Hypertext Markup Language (HTML)

HTML is a computer language, which was developed to mark up, or encode hypertext document for display on the World Wide Web. An HTML document is a plain ASCII (text) file with codes (called tags) inserted in the text to define elements in the document. HTML tags generally have 2 parts, an on-code and an off-code, which contain the text to be defined. However, a few tags do not require an off-code.

A tag can be represented in the following way, where the ellipsis (...) represents the text you want to tag:

<Tagname> ... </Tagname>

For example, the following is the tag for a level-one heading in a Web document:

<H1>This is a level-one heading</H1>

HyperText Transfer Protocol (HTTP)

HTTP is a plain text protocol that defines how the Web transports Web pages. Although an understanding of HTTP is not strictly necessary for the development of CGI applications, some appreciation of "what's under the hood" will certainly help you to develop them with more fluency and confidence. As with any field of endeavour, a grasp of the fundamental underlying principles allows you to visualise the structures and processes involved in the CGI transactions between clients and servers - giving you a more comprehensive mental model on which to base your programming.

Underlying the user interface represented by browsers, is the network and the      protocols that travel the wires to the servers or "engines" that process requests, and       return the various media. The protocol of the web is known as HTTP, for Hypertext Transfer Protocol. HTTP is the underlying mechanism on which CGI operates, and it directly determines what you can and cannot send or receive via CGI.

Tim Berners-Lee implemented the HTTP protocol in 1990-1 at CERN, the European Center for High-Energy Physics in Geneva, Switzerland. HTTP stands at the very core of the World Wide Web. According to the HTTP 1.0specification,

The Hypertext Transfer Protocol (HTTP) is an application-level protocol with the lightness and speed necessary for distributed, collaborative, hypermedia information systems. It is a generic, stateless, object-oriented protocol which can be used for many tasks, such as name servers and distributed object management systems, through extension of its request methods (commands).