Internet

Concept and Terminology

The Internet

• The Internet is the largest computer system in the world.

• The Internet is often called the Net, the Information Superhighway or Cyberspace.

• The Internet consists of thousands of connected networks around the world. A network is a collection of computers that are connected to share information.

How do computers communicate ?

protocols

TCP/IPProtocol

• a set of rules governing how things are to be done

TCP/IP (Transmission Control Protocol/ Internet Protocol)

• a collective term of protocols used in Internet, governing .– the format of the messages transmitted– how the messages transmitted along the Internet

TCP/IPTCP• set rules on managing the correctness and the flow of

the data

IP

• set rules of transmitting raw data along the Internet

TCP/IP

• set up rules for providing error-free channels for transmission

UNIX

• It is a family of operating systems most widely used in the computer world

• It is used by most of computers in the Internet

• The UNIX commands can be used in the Internet

How to identify a host computer?

DOMAIN/ HOST name

physical address

IP addressing

If only domain name is known, how do you know the IP address ?

DNS

Domain Name System (DNS)• DNS servers on the Internet resolve Host/Domain n

ames into IP addresses for locations on the Internet

• It can do reverse lookup

• Domain Name are registered and recognised throughout the Internet

• Use on the Internet and on Intranet for all TCP/IP hosts– e.g. www.microsoft.com may be resolved to

a 32-bit binary address 207.46.130.149

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.

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.

Web page /Web site address

Web page.

• It is a hypertext (HTML) document contained in a single file

Web site address

• the address that can identify the Web page

Homepage

• It serves 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.

How do the Web pages transfer along the Internet ?

protocol

HyperText Transfer Protocol (HTTP)

• HTTP is a plain text protocol that defines how the Web transports Web pages.

• An understanding of detail mechanism is not necessary

• It directly determines what you can and cannot send or receive through the Internet

Internet Service Provider (ISP)

• A company or organization provides you access to the Internet

• It may also give you space for a personal or non-commercial Web site at little or no cost

Internet address

• 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

Internet address

– Next is the address of the computer (server) on which the site is stored.

– It also include a page name or address that identifies a specific page within a site.

For examplehttp://www.microsoft.com/windows/abc.html

Uniform Resource Locator (URL)

For examplehttp://www.microsoft.com/windows/abc.html

Protocol

computer address

Path on Web server

HTML file