1. The Internet and the World Wide Web WWW
Chapter 1

2. The Internet Wikipedia: http://en.wikipedia.org/wiki/Internet
a connection of computer networks using the Internet Protocol (IP)
layers of communication protocols: IP → TCP/UDP → HTTP/FTP/POP/SMTP/SSH...
What's the difference between the Internet and the World Wide Web (WWW)?
The Web is the collection of web sites and pages around the world; the Internet is larger and also includes other services such as , chat, online games, etc.

3. More Officially, What is the difference between the Web and the Internet?
From the definition in the Wikipedia: "The Internet is a global system of interconnected computer networks that interchange data by packet switching using the standardized Internet Protocol Suite (TCP/IP)."
Thus, the Internet is a network of networks, defined by the TPC/IP standards.
The Web, on the other hand, is defined in W3C's Architecture of the World Wide Web, Volume I as follows: "The World Wide Web (WWW, or simply Web) is an information space in which the items of interest, referred to as resources, are identified by global identifiers called Uniform Resource Identifiers (URI)."
Thus, the Web is an information space. The first three specifications for Web technologies defined URLs, HTTP, and HTML
Source:

4. Internet History

5. Brief history
Began as a US Department of Defense network called ARPANET (1960s- 70s)
Initial services: electronic mail, file transfer
Opened to commercial interests in late 80s
WWW created in by Sir. Tim Berners-Lee

6. The Internet 1971 - ARPANET has 23 hosts
TimeLine for the internet development
Source:

7. Key aspects of the internet
subnetworks can stand on their own
computers can dynamically join and leave the network
built on open standards; anyone can create a new internet device
lack of centralized control (mostly)
everyone can use it with simple, commonly available software

8. Who "runs" the internet? Who is responsible for overseeing it?

9. People and organizations
Internet Engineering Task Force (IETF): internet protocol standards.
Internet Corporation for Assigned Names and Numbers (ICANN):  decides top-level domain names
World Wide Web Consortium (W3C): web standards.
These protocols are carried out in large part by internet service providers and other companies and organizations who build internet- related products and applications.

10. Layered architecture
The internet uses a layered hardware/software architecture (also called the "OSI model"):
physical layer : devices such as Ethernet, coaxial cables, fiber-optic lines, modems
data link layer : basic hardware protocols (Ethernet, Wi- Fi, DSL PPP)
network / internet layer : basic software protocol (IP)
transport layer : adds reliability to network layer (TCP, UDP)
application layer : implements specific communication for each kind of program (HTTP, POP3/IMAP, SSH, FTP)

11. Layers of protocol Protocol:
A set of rules governing the format of data sent.

12. Internet Protocol (IPv4git)
a simple protocol for attempting to send data between two computers
each device has a 32-bit IP address written as four 8-bit numbers (0-255) 
Find out your internet IP address: whatismyip.com
find out your local IP address:
in a terminal, type: ipconfig (Windows) or ifconfig (Mac/Linux)

13. Transmission Control Protocol (TCP)
adds multiplexing, guaranteed message delivery on top of IP
multiplexing: multiple programs using the same IP address
port: a number given to each program or service
port 80: web browser (port 443 for secure browsing)
port 25:
port 22: ssh
port 5190: AOL Instant Messenger
more common ports
some programs (games, streaming media programs) use simpler UDP protocol instead of TCP

14. World Wide Web (WWW)

15. The World Wide Web (WWW)
Wait, how is it different than the internet again?
The internet describes all the interconnected devices that use the "internet protocol." The world wide web is the subset of the internet that uses the http and https protocols, mostly to transmit "webpages."

16. The World Wide Web (WWW)
web server: software that listens for web page requests
Apache
Microsoft Internet Information Server (IIS) (part of Windows)
web browser: fetches/displays documents from web servers
Mozilla Firefox
Microsoft Internet Explorer (IE)
Apple Safari
Google Chrome
Opera

17. WWW History

18. Hypertext Vannevar Bush 1945 Essay, “As We May Think”
“The memex was also to be a storage and retrieval device using microfilm. It would consist of a desk with viewing screens, a keyboard, selection buttons and levers, and microfilm storage. Information stored on the microfilm could be retrieved rapidly and projected on a screen. The machine was to extend the powers of human memory and association. Just as the human mind forms memories through associations, the user of the memex would be able to make links between documents.” ( )
Ted Nelson coined the word hypertext in the 1960’s and credits Bush.
Current project:
Source:

19. Xanadu Ted Nelson coined the word hypertext in 1965
Envisioned Xanadu as a tool to preserve and increase humanity’s literature and art.
Information stored as connected literature
Source:

20. TimeLine for the W3C development.

21. Sir. Tim Berners-Lee
1989 wrote a proposal to solve information sharing problem at CERN
CERN: In French "Conseil Européen pour la Recherche Nucléaire", or European Council for Nuclear Research,
1990 wrote HTML, HTTP, URI
1991 available outside CERN
1994 moved to MIT to found W3C
Source:

22. World Wide Web Browser
End 1990: Development begins for first browser (called "WorldWideWeb"), editor, server, and line- mode browser. Culminates in first Web client-server communication over Internet in December 1990

23. Web as a Poster !!!!!!!
Dec: Hypertext '91 Conference in San Antonio, Texas (USA). TBL paper on Web only accepted as poster session.

24. Early Browsers
Marc Andreessen and other students at NCSA developed Mosaic.
NCSA: National Center for Supercomputing Applications
0.1a released in 1993
supported by NSF funding

25. Early Browsers Andreessen founded Netscape Communications Corp.
1996: 75% of web users used Netscape
Many browser features originated with Netscape
cookies, frames, Javascript
Browser wars with Microsoft and increasingly buggy software led to Netscape’s demise
1998 released code base to open source -> Mozilla was born

26. Lynx
Terminal-based web browser

27. Search Excite 1993 Yahoo! Directory 1994 Lycos 1994 AltaVista 1995
Inktomi 1996
Google

28. Internet Archive - Old Version of Websites

29. Economic Shifts Internet economy GDP share:
Canada 3.6%
USA 5.4%
China 6.9%
UK 12%(?)
Projections are that half of the world’s population currently use the Internet

30. Domain Name System (DNS)
a set of servers that map written names to IP addresses
Example: 
How the Domain Name System (DNS) Works
Check the following Link
many systems maintain a local cache called a hosts file
Windows: C:\Windows\system32\drivers\etc\hosts
Mac: /private/etc/hosts
Linux: /etc/hosts

31. Domain Name System (DNS)
an identifier for the location of a document on a web site
a basic URL:
~~~~ ~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~
protocol host path
upon entering this URL into the browser, it would:
ask the DNS server for the IP address of 
connect to that IP address at port 80
ask the server to GET /info/regesstepp/index.html
display the resulting page on the screen

32. More advanced URLs anchor: jumps to a given section of a web page
fetches index.html then jumps down to part of the page labeled downloads
port: for web servers on ports other than the default 80
query string: a set of parameters passed to a web program
parameter q is set to "miserable+failure"
parameter start is set to 10

33. Hypertext Transport Protocol (HTTP)
The set of commands understood by a web server and sent from a browser
some HTTP commands (your browser sends these internally):
GET filename : download
POST filename : send a web form response
PUT filename : upload
simulating a browser with a terminal window:
$ telnet 80
Trying
Connected to ( ).
Escape character is '^]'.
GET /index.html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML ">
<html>
...

34. HTTP error codes
When something goes wrong, the web server returns a special "error code" number to the browser, possibly followed by an HTML document
common error codes:
Number Meaning
200 OK
page has moved (permanently or temporarily)
403 you are forbidden to access this page
404 page not found
500 internal server error
complete list

35. Internet media ("MIME") types
sometimes when including resources in a page (style sheet, icon, multimedia object), we specify their type of data
MIME type file extension
text/html .html
text/plain .txt
image/gif .gif
image/jpeg .jpg
video/quicktime .mov
application/octet-stream .exe
Lists of MIME types: by type, by extension

36. Web languages / technologies
Hypertext Markup Language (HTML): used for writing web pages
Cascading Style Sheets (CSS): stylistic info for web pages
PHP Hypertext Processor (PHP): dynamically create pages on a web server
JavaScript: interactive and programmable web pages
Asynchronous JavaScript and XML (Ajax): accessing data for web applications
eXtensible Markup Language (XML): metalanguage for organizing data
Structured Query Language (SQL): interaction with databases