Introduction To Internet
The internet (here onwards referred to as NET) is a collection of information stored in computers physically located throughout the world; really a network of computers that exchange information with each other. The word Internet comes from the term internetworking, which means, “to communicate between networks”.
The Internet is a way to do two things:
- Communicate with people
- Retrieve information
The Internet from two aspects:
- As a hardware, the Net is a global collection of million computers we call hosts, computers that offer information and services to other computers. Signals travel to and from all these hosts and eventually to you, through a maze of wires and fiber optic cable.
- As a software, the Net productivity is achieved by programs that allow you to send and receive electronic mail, log into other networks, transfer computer files to and from host systems that stores files, and share and capture useful data and information.
Brief History of Internet
|1957||The Soviet Union launches Sputnik. One US response is to form the Advanced Research projects Agency (ARPA) whose mission is to develop ways to put US technology ahead of foreign powers and keep it there. ARPA later becomes DARPA, with the D standing for Defense.|
|1962||Packet-switching technology is proposed. The goal is for one computer to “talk: to any other computer regardless of its type.|
|1969||The first network is designed with the vision of 1962 in mind. The protocol behind this success is the NCP (Network Control Protocol).|
|1972||E-mail is born.|
|1973||The fledgling packet-switching network goes international to Great Britain and Norway.|
|1979||USENET newsgroup are born.|
|1981||The concept of mailing lists is born with the BITNET.|
|1982||TCP/IP replaces NCP as the primary “interneting” protocol.|
|1984||The FQDN (Full Qualified Domain Name) system is born.|
|1986||NSFNET, the non-profit National Science Foundation Network is born. NSFNET links educational institutions the government, the military, think tanks, and the five supercomputing centres.|
|1989||The World Wide Web is born.|
|1990||The original ARPANET is retired.|
|1991||Gopher and WAIS are born. CIX, the Commercial Internet Exchange, is also born to give some weight to commercial companies who want to “Internet” and send packets around the commercially owned backbones. These backbones links to the NSFNET, so that the aforementioned non-commercial facilities have communication access to the commercial backbones.|
|1993||Mosaic World-Wide-Web browser is born.|
What is the Internet
The Internet is a global connection of computers. These computers are connected via a huge network of telecommunication links. The communication links which interconnect each host computer use a common method of transmission, known as TCP/IP, which stands for Transmission Control Protocol/Internet Protocol.
Each host on the Internet has a unique TCP/IP address, a four digit number separated it by dots. An example address is 18.104.22.168 which is the TCP/IP address of the computer which acts as a host for Pacific Internet. Data is sent from the user with the destination address specified as the host computer. The host computer, when sending data back to the user, specifies the destination address of the user.
Servers are host computers which provide a service to users. Other type of servers are WWW (world-wide-web) server, ftp (file-transfer-protocol) servers, gopher servers, mail servers, and news servers. Each server uses a specific protocol or method of communication based on TCP/IP.
Internet Service Providers are companies which provide others with access to the Internet. This can be via dial-up connection using a modem, or using an ISDN or permanent high speed connection. Various charging levels may exist, but a popular method for home users is flat rate (per month unlimited time and data amount).
Traditionally the Internet was purely a text based global pool of information and access was either limited or required a certain specialised knowledge. The development of the Internet today has ensured that information now comes in other formats such as graphical, audio, video and animated images, and the interface for such information is now a lot more dynamic and user-friendly.
What is the World Wide Web
The World Wide Web is a collection of host machines which deliver documents, graphics and multi-media to users via the Internet or an Intranet. Pages or files are stored on Web Servers. Users access these pages using a graphical browser like Netscape Navigator or Internet Explorer.
When a client requests a document or file, a connection is made to that computer using the HTTP protocol. The WWW server services the request, locates the information, and sends it back to the client. The connection between the client and the WWW is then released. The client browser software then interprets the retrieved HTML document and formats it on the client computer screen.
A hyperlink is a clickable link to another document or resource. It is normally shown in blue underline. When a user clicks on this link, the client will retrieve the document associated with that link, by requesting the document from the designated server upon which it resides.
A Uniform Resource Locator is a mess of specifying the pathname for any resources on the Internet or an Intranet. It consists of three parts:
- a protocol part
- a host part
- a document part
For instance, the following URL,
specifies the protocol as http, the host or WWW server as www.sirjet.net and the document as /index.html
Servers or host computers are arranged according to geographical location. For instance, all countries in the world have a country suffix, except the USA. New Zealand’s suffix is nz, while Canada is ca. Typically, the host part of a URL looks like:
- name organization name
- type of of organization
- country name
➡ The features of World Wide Web (WWW) are,
- server provides WWW access
- information presented as pages
- uses html to write pages
- pages may reference other pages, graphics, etc.
- pages written in html
- pages may invoke programs to process user supplied data
- client provides browse services to view pages and handle special page types
- connect only long enough to get a page
- special types of pages are called mime types
- the handling of mine types is left to the browser
- available servers are CERN, HTTPS, NCSA, etc.
- available browsers are Internet Explorer, Google Chrome, Mozilla Firefox, etc.
Introduction To HTML
Webpage: Information in the Internet are organized in terms and specially formatted pages which are called Webpage. A Webpage may contain text, images, graphics sound clips, video clips, etc. This content of a webpage contains links to other Webpages in terms of Hypermedia links. One Webpage may contain numerous links to other different pages.
Uniform Resource Locator (URL): Each webpage in the Internet needs to have a unique address in order to locate it through links. These unique address are called Uniform Resource Locator, URL for short. URL’s may appear in different format to define the type of information it contains. For example, “http://www.sirjet.net/” contains hyper text documents, “www.cnn.com” contains news group articles, and so on.
HTML: The language used by the Web is called HTML, which stands for Hyper Text Markup Language. The Hyper Text part means that a Web page can contain references to other Web pages or to various net resources. The Markup part comes from the days when book and magazine publishing people made special marks on their author’s manuscripts to tell typesetters how to format the text. This process was called Markup, and the term was adopted when people started inserting formatting instructions into their computer files.