1. Internet

2. Briefly explain a short history of the Internet
Briefly explain a local area network (LAN) and wide area network (WAN)
Briefly explain servers and clients
Understand how the Internet works (on a basic level)

3. History A Brief History of the Internet
In 1969, the US Department of Defense started a project to allow researchers and military personnel to communicate with each other in an emergency. The project was called ARPAnet and it is the foundation of the Internet.
Throughout the 1970's, what would later become the Internet was developed. While mostly military personnel and scientists used it in its early days, the advent of the World Wide Web in the early 1990's changed all that.
Today, the Internet is not owned or operated by any one entity. This worldwide computer network allows people to communicate and exchange information in new ways.

4. What is the Internet? What is the Internet?
The Internet is the largest computer network in the world, connecting millions of computers. A network is a group of two or more computer systems linked together.
There are two types of computer networks:
Local Area Network (LAN): A LAN is two or more connected computers sharing certain resources in a relatively small geographic location (the same building, for example).
Wide Area Network (WAN): A WAN typically consists of 2 or more LANs. The computers are farther apart and are linked by telephone lines, dedicated telephone lines, or radio waves. The Internet is the largest Wide Area Network (WAN) in existence.

6. Servers
Servers
All computers on the Internet (a wide area network, or WAN) can be lumped into two groups: servers and clients. In a network, clients and servers communicate with one another.
A server is the common source that :
Provides shared services (for example, network security measures) with other machines
AND
Manages resources (for example, one printer many people use) in a network.
The term server is often used to describe the hardware (computer), but the term also refers to the software (application) running on the computer. Many servers are dedicated, meaning they only perform specific tasks.
For example,
An server is a computer that has software running on it allowing it to "serve" -related services.
A web server has software running on it that allows it to "serve" web-related services.

7. Clients
Clients
Remember, all computers on the Internet (a wide area network, or WAN) can be lumped into two groups: servers and clients, which communicate with one another.
Independent computers connected to a server are called clients. Most likely, your home or office computer does not provide services to other computers. Therefore, it is a client.
Clients run multiple client software applications that perform specific functions.
For example,
An application such as Microsoft Outlook is client software.
Your web browser (such as Internet Explorer or Netscape) is client software.

8. Communication Servers and Clients Communicate
Your computer (client hardware) is running a web browser such as Internet Explorer (client software).
When you want to surf the web, your browser connects to a remote server and requests a web page.
The remote server (server hardware) runs web server software (server software).
The web server sends the web page to your computer's web browser.
Your web browser displays the page.

9. Protocols
When two humans converse, they may have to use the same language but they generally understand each other without having to adhere to rigid rules of grammar or formal language frameworks. Computers, on the other hand, have to have everything explicitly defined and structured. If computers wish to communicate with one another, they have to know in advance exactly how information is to be exchanged and precisely what the format will be. Therefore, standard methods of transmitting and processing various kinds of information are used and these methods are called "protocols". Protocols are established by international agreement and ensure that computers everywhere can talk to one another. There are a variety of protocols for different kinds of information and functions. This article will discuss some of the common protocols that the average PC user is likely to encounter.

10. TCP/IP
TCP/IP
TCP (Transmission Control Protocol) and IP (Internet Protocol) are two different procedures that are often linked together. The linking of several protocols is common since the functions of different protocols can be complementary so that together they carry out some complete task. The combination of several protocols to carry out a particular task is often called a "stack" because it has layers of operations. In fact, the term "TCP/IP" is normally used to refer to a whole suite of protocols, each with different functions. This suite of protocols is what carries out the basic operations of the Web. TCP/IP is also used on many local area networks. The details of how the Web works are beyond the scope of this article but I will briefly describe some of the basics of this very important group of protocols. More details can be found in the references in the sidebar. (Incidentally, one characteristic of AOL is that they do not use the standard TCP/IP. Thus their network is a sort of separate "gated" community.)
When information is sent over the Internet, it is generally broken up into smaller pieces or "packets". The use of packets facilitates speedy transmission since different parts of a message can be sent by different routes and then reassembled at the destination. It is also a safety measure to minimize the chances of losing information in the transmission process. TCP is the means for creating the packets, putting them back together in the correct order at the end, and checking to make sure that no packets got lost in transmission. If necessary, TCP will request that a packet be resent.

11. TCP/IP
Internet Protocol (IP) is the method used to route information to the proper address. Every computer on the Internet has to have it own unique address known as the IP address. Every packet sent will contain an IP address showing where it is supposed to go. A packet may go through a number of computer routers before arriving at its final destination and IP controls the process of getting everything to the designated computer. Note that IP does not make physical connections between computers but relies on TCP for this function. IP is also used in conjunction with other protocols that create connections.
Another member of the TCP/IP suite is User Datagram Protocol (UDP). (A datagram is almost the same as a packet except that sometimes a packet will contain more than one datagram.) This protocol is used together with IP when small amounts of information are involved. It is simpler than TCP and lacks the flow-control and error-recovery functions of TCP. Thus, it uses fewer system resources.
A different type of protocol is Internet Control Message Protocol (ICMP) . It defines a small number of messages used for diagnostic and management purposes. It is also used by Ping and Traceroute.

12. Mail protocols Mail protocols
requires its own set of protocols and there are a variety, both for sending and for receiving mail. The most common protocol for sending mail is Simple Mail Transfer Protocol (SMTP). When configuring clients such as Outlook Express, an Internet address for an SMTP server must be entered. The most common protocol for receiving mail is Post Office Protocol (POP). It is now in version 3 so it is called POP3. clients such as Outlook Express require an address for a POP3 server before they can read mail. The SMTP and POP3 servers may or may not be the same address. Both SMTP and POP3 use TCP for managing the transmission and delivery of mail across the Internet.
A more powerful but less common protocol for reading mail is Internet Mail Access Protocol (IMAP). This protocol allows for the reading of individual mailboxes at a single account and is more common in business environments. IMAP also uses TCP to manage the actual transmission of mail.
It is increasingly popular to use Web based such as Yahoo. Web mail, of course, involves the same protocol as a Web page and this is discussed next.

13. The Mail Protocol Suite
One thing to note is that there a several mail protocols and there are different ones for sending mail (e.g. SMTP) and reading mail (e.g. POP).
The Most common Mail Protocols include:
SMTP
-- Simple Mail Transfer Protocol (more below)
POP3
-- Post Office Protocol (more below)
IMAP
-- Internet Message Access Protocol. It is a method of accessing electronic mail or bulletin board messages that are kept on a (possibly shared) mail server. In other words, it permits a "client" program to access remote message stores as if they were local. For example, stored on an IMAP server can be manipulated from a desktop computer at home, a workstation at the office, and a notebook computer while traveling, without the need to transfer messages or files back and forth between these computers.
MIME
-- Multipurpose Internet Mail Extensions. Defines the standard representation for "complex" message bodies. A "complex" message body doesn't conform to the default of a single, human-readable, ASCII mail message. Examples of "complex" message bodies include messages with embedded graphics or audio clips, messages with file attachments, messages in Japanese or Russian, or signed messages.

14. HTTP Hypertext Transfer Protocol
Web pages are constructed according to a standard  method called Hypertext Markup Language (HTML). An HTML page is transmitted over the Web in a standard way and format known as Hypertext Transfer Protocol (HTTP). This protocol uses TCP/IP to manage the Web transmission.
A related protocol is Hypertext Transfer Protocol over Secure Socket Layer (HTTPS), first introduced by Netscape. It provides for the transmission in encrypted form to provide security for sensitive data. A Web page using this protocol will have https: at the front of its URL.

15. File Transfer Protocol
File Transfer Protocol (FTP) lives up to its name and provides a method for copying files over a network from one computer to another. More generally, it provides for some simple file management on the contents of a remote computer. It is an old protocol and is used less than it was before the Word Wide Web came along. Today, Its primary use is uploading files to a Web site. It can also be used for downloading from the Web but, more often than not, downloading is done via HTTP. Sites that have a lot of downloading (software sites, for example) will often have an FTP server to handle the traffic. If FTP is involved, the URL will have ftp: at the front.

16. FTP One of the protocols within the TCP/IP protocol suite
Is used to facilitate the transfer of files from one host to another
User can use FTP to transfer files to/from two hosts when they possess an account on each host
Internet users may receive files from hosts which have been set up with anonymous FTP
Anonymous FTP
Anonymous FTP accounts have been set up on hosts which have been designated archive sites
These accounts have limited access rights, as well as some operating restrictions

17. FTP commands
delete mdelete put dir mget pwd ascii disconnect mkdir quit binary get mode bye mput rename verbose cd help cdup lcd open rmdir close ls prompt etc..

18. FTP The commands that can be used to retrieve files are: get mget
remote-file [ local-file ] -- Retrieve the remote-file and store it on the local machine. If the local file name is not specified, it is given the same name it has on the remote machine, subject to alteration by the current case recv
remote-file [ local-file ] -- The same as for get .
mget
remote-files -- Multiple Get: Expand the remote-files on the remote machine and do a get for each file name thus produced. The mget command is typically used with wild cards . The setting of the prompt is also useful for ues with mget
prompt
-- Toggle interactive prompting. Interactive prompting occurs during multiple file transfers to allow the user to selectively retrieve or store files. By default, prompting is turned on. If prompting is turned off, any mget or mput will transfer all files, and any mdelete (see below also) will delete all files.

19. FTP The commands that let you upload files are: put send append mput
local-file [ remote-file ] -- Store a local file on the remote machine. If remote-file is left unspecified, the local-file name is used
send
local-file [ remote-file ] -- The same as for put.
append
local-file [ remote-file ] Append a local file to a file on the remote machine. If remote-file is not specified, the local file name is used
mput
local-files -- Multiple put: Expand wild cards in the list of local files given as arguments and do a put for each file in the resulting list.

20. Telnet
What is Telnet
The Telnet protocol is often thought of as simply providing a facility for remote logins to computer via the Internet. This was its original purpose although it can be used for many other purposes.
It is best understood in the context of a user with a simple terminal using the local telnet program (known as the client program) to run a login session on a remote computer where his communications needs are handled by a telnet server program. It should be emphasized that the telnet server can pass on the data it has received from the client to many other types of process including a remote login server.

21. Telnet Some practical uses of Telnet include:
Telnet is a Protocol that lets you use the power of the Internet to connect you to databases, library catalogs, and other information resources around the world.
Telnet lets you connect directly to another computer on the Internet and run programs on the computer (provided you have access permission (Username and Password).
Theoretically you have a lot of power at your fingertips. Your dumb terminal or very old PC can run programs on the worlds most powerful computers.
Several Telnet Clients exist on most platforms telnet on UNIX/DOS, NiftyTelnet/BetterTelnet PPC on Macs etc.
Telnet may have a few practical drawbacks also
Telnet is old. It is text based only.
You have to know how to run programs at the other end.
Different Computer System
Different Commands, Directory Structures
Different Language -- Programming and ``spoken''

22. Usenet
What is Usenet?
Is a large collection of discussion groups, accessible via the Internet, involving millions of people from all over the world
Has over 30,000 discussion groups of regional or local interest
Is free, but requires access to a news server
There is no central authority which controls Usenet
There are well established procedures for forming new non-local discussion groups

23. Usenet Differences Between Usenet and Internet
Usenet was chosen as an abbreviation for user's network
However, name is misnomer since Usenet is not really a physical network of computers linked together
The Internet, however, is a collection of tens of thousands of networks worldwide
Internet is a general purpose carrier of information whereas the Usenet is one type of service that makes use of this capability
Is every Internet computer part of Usenet?
No, since many Internet computers are owned by people who choose not to participate in Usenet
To be part of Usenet requires that someone act as administrator and a computer with a large amount of disk space available to hold news articles and programs

24. WWW What is the World Wide Web? One simple definition of the WWW is:
The WWW is a Hypertext Information System
Hypertext browsing:
Non-linear structure (not a book)
You read what you want next
Click on Hypertext links to navigate the WWW.
What is Hypertext?
Hypertext is a method of presenting information where selected words in the text can be expanded at any time to provide other information about the word
i.e these words are links to other documents which may be text, files, pictures, anything.
Links can be identified by highlighted (underlined) and coloured text

25. Other features of the WWW include: Graphical Easy to use
HTML (Hypertext Markup Language) is the language used to create WWW pages and associated links (e.g. URLs which we have already met).
Other features of the WWW include:
Graphical
-- by definition text, graphics and other media can coexist on Web page.
Easy to use
-- hypertext and good WW browsers are intuitive tools to use.
Cross-platform
-- One big advantage is that WWW (html pages etc) can run on almost any computer.
Distributed
-- Information and resources shared globally.
Dynamic
-- Information on the WWW can be constantly updated (unlike a book or CD-ROM). Live information can assimilated.
Interactive
-- through forms and other tools (e.g. Java) the WWW can be made interactive.

26. Web Browsers Web Browsers
A Web browser is a special application that reads Web pages.
Common WWW browsers include:
Internet Explorer
-- Microsoft's Browser the most popular browser to date (By Hook or by crook - ask the US Judiciary). A competitor to Netscape Navigator.
Netscape Navigator
-- First Commercial browser, originated from Mosaic.
Mosaic
-- the first graphical browser.
Lynx
-- Text only browser.

27. Web Servers Web Servers
To view and browse information on the web all you need is a browser.
To publish and deliver information of the web you need a Web server.
A web server is a program that runs on web sites and is responsible for replying to a web browser request for files.
Client (Browser) Server interaction
When a browser requests a Web page:
the browser makes a connection to a server using http protocol.
the server then
accepts the connection,
sends the files contents back to browser, and
closes the connection.
the browser then formats the (html) information received.

28. Gopher
The Gopher technology was invented at the University of Minnesota, whose mascot is, not surprisingly, the Golden Gopher. The gopher system allows people to search for and retrieve information using a text interface. The technology is based on a client-server structure, where a gopher client program is used to search gopher servers. These servers can store documents, articles, programs, and other information. Instead of hyperlinks, the gopher interface uses menus of links to other documents and programs. The University of Minnesota began a licensing program for the gopher technology in 1993 as the use of gopher was spreading rapidly over the Internet. However, this was around the same time that the World Wide Web was introduced. Because the Web used hypertext and images, it soon became the preferred way to search and browse for information. While there are still servers and client programs that use gopher technology, their use is not nearly as widespread as the Web.

29. WAIS
Stands for "Wide Area Information Server." This is a program that can index enormous amounts of information and make it searchable across large networks (including the Internet). People can search the WAIS index and it will return results by relevance. Searches can then be narrowed down by subsequent searches on the original results. Search engines are a new and improved version of WAIS, specifically for the Web.

30. Port no
This is a number that indicates what kind of protocol a server on the Internet is using. For example, Web servers typically are listed on port 80. Web browsers use this port by default when accessing Web pages, but you can also specify what port you would like to use in the URL like this: FTP uses port 21, uses port 25, and game servers, like a Quake server or Blizzard.net use various other ports.

31. FTP 20/21
Telnet 23
SMTP 25
HTTP 80
GOPHER 70
POP3 110

32. Basic HTML tags Summary of Basic HTML Tags Head Elements
Marks properties of entire document
Marked with <head>
Includes title <title> tag
Ended with </head>
Body Elements
Marked with <body>
Header levels <h1>, <h2>, <h3>, etc.
Anchors <a href= " text</a>
Paragraph indicators <p>
Line breaks <br>
Horizontal line <hr>
Address tags <address>
Blockquote style <blockquote>
Within a body text may be organised in variety of ways:

33. Lists
Unordered <ul> with <li> (list item)
Ordered <ol> with <li>
Definition <dl> with <dt> and <dd>
Menu <menu> with <li>
Short <dir> with <li>
Preformatted text
<pre>
Character formatting (physical)
Bold <b>
Italics <i>
Underline <u>
Fixed width <tt>

34. Character formatting (logical)
Strong <strong>
Variable name <var>
Citation <cite>
Graphics
In-line images <img src=³image.gif²>
Include alt=³ ³ for browsers that can¹t display graphics, e.g. <img src=³image.gif² alt=³Image GIF²>
Entities
Character strings that represent special symbols, e.g.
&amp for ``&``
&gt for ``>``
&quot for double quote (``)