INTERNET and WWW

Internet
- an international computer network providing e-mail and information from computers in educational institutions, government agencies, and industry, accessible to the general public via modem links.

History
- It began way back 1969
- Originally called ARPANET
( Advanced Research Projects Agency Network)
- Its purpose was to survive a nuclear war.
- In 1979 - Usenet was born
- In 1983 - TCP/IP was established

Internet Services

E-mail
- messages distributed by electronic means from one computer user to one or more recipients via a network.
the system of sending messages by such electronic means

Newsgroup
- a group of Internet users who exchange e-mail messages on a topic of mutual interest

FTP
- file transfer protocol, a standard for the exchange of program and data files across a network.

Archie (Archive Listing Service)
- A system used to locate various public domain programs stored on hundreds of sites all over the world.

Chat
- A virtual community where people from all over the world can communicate on-line by exchanging text data at almost real-time.

Gopher
- a menu-based system that allows users of the Internet to search for and retrieve documents on topics of interest.

WAIS
- Wide Area Information Service, designed to provide access to information across a computer network.

TELNET
- a network protocol that allows a user on one computer to log on to another computer that is part of the same network.

WWW
- a widely used information system on the Internet that provides facilities for documents to be connected to other documents by hypertext links, enabling the user to search for information by moving from one document to another.

History of WWW

- came from CERN
- Its inventor is Tim-Berners Lee
- Was implemented by 1992

Hypertext / Hypermedia

* Hypertext (coined by Ted Nelson in 1965) is a software system that links topics on the screen to related information and graphics, which are typically accessed by a point-and-click method
*Hypermedia is an extension to hypertext providing multimedia facilities, such as those handling sound and video.

How data is transferred from one computer to another?
- A piece of data is broken up into chunks
( whole-lot of same size pieces called packets)
- Each packet is sent from computer to computer
- TCP/IP receives, sends and checks packets.

Web Browser / Web Server

* Browser is a program with a graphical user interface for displaying HTML files, used to navigate the World Wide Web.
*Server is a computer that responds to requests from a web browser.

HTTP
- A set of rules for exchanging files ( text, graphic images, sound, video and other multimedia files) on the world wide web.

Uniform Resource Locator
- A full address used by a web browser to request information on the world wide web.

Parts of the URL

Parts of a Browser

- Back Button -Forward button -Home -Reload or Refresh -Print - Stop
- Bookmarks or Favorites - Address bar - Access Indicator -Status bar -Scroll bar

Internet Programming Language

*XML – Extensible Markup Language
*Java Programming – is an object-oriented,
*PERL – Practical Extraction Report Language
*ASP – Active Server Pages allows developer to utilize a web server.
*JSP – Java Server Pages
*CFML – Cold Fusion Mark-up Language
*CGI – Common gateway Interface

Multimedia - various collection of :
- Graphics
- Sounds
- Animations
- Videos

Graphics Formats:

* BMP – Bitmapped graphics (.bmp)
Standard bit-map graphics format for windows.
* TIFF – Tagged Image File Format (.tiff)
* GIF – Graphics Interchange format
- it supports color and various resolution limited to 256 colors
* JPEG – Joint Photographic Experts Group
lossy compression technique for color images
* PNG – Portable network graphics
a new bit mapped graphics format similar to gif

Sound Formats
*AIFF – Audio Interchange File Format
Common Format for storing and transmitting sounds
*MIDI – Musical Instrument Digital Interface
Standard adopted by the electronic music for controlling devices such as synthesizers and sound cards that emit music.
*MP3 – MPEG Audio Layer 3
Uses perceptual audio coding and psycho acoustic compression
*AU – Audio
Common formats for sound files on UNIX machines
*WMA – Windows Media Audio
microsofts response to MP3, The windows media audio standard.
*WAV – Wave
sound format developed by IBM and Microsoft

Video Formats
*Mov – Movie
*AVI – Audio Video Interleave
*MPEG/ MPG – Moving Picture Experts Group
(working group of ISO)

PLUG-INS
*SWF and Flash player Shockwave Flash
*Shockwave

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