Internet

Internet and World Wide Web

The internet is a global system of interconnected computer networks that interchange data by packet switching using the standardized internet protocol suite (TCT/IP). It is a network of networks that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by copper wires, fiber-optic cables, wireless connections, and other technologies. The internet carries various information resources and services, such as electronic mail, online chat, file transfer and file sharing, online gaming, and the inter-linked hypertext documents and other resources of the World Wide Web.

Any single individual, company, or country does not own this global network. A network of networks or internet is a group of two or more networks that are:

v     interconnected physically

v     capable of communicating and sharing data with each other

v     able to act together as single network.

Machines on one network can communicate with machines on other networks, and send data, files, and other information back and forth. For this to work, the networks and machines that are part of the internet have to agree either to speak the same language when they are communicating or to use an interpreter. This language is software is that enables the different types of machines on separate networks to communicate and exchange information. To be used by different types of machines and yet be understood by all of them, the software must follow a set of rules, or protocol.

The internet, with a capital "I", is the network of networks, which either uses the TCP/IP protocol or interacts with TCP/IP networks via gateways. The internet  presents these networks as one, seamless network for its users. The internet covers the globe and includes large international networks as well as many smaller, local area networks (LAN). The internet offers access to data, graphics, sounds, software, text, and people through a variety of services and tools for communication and data exchange.

• Remote login (Telnet)
• File transfer (FTP)
• Electronic mail (E-mail)
• News (usesnet or network news)
• Hypertext (WWW)

Compiling information from the inernet

This is obviously a special case of getting information. The distinction is that it is possible to get specialized information from the web. For instance, if you wanted to poll the readership for a magazine or conduct a survey to detect the pulse of a selected community, the web provides you with the ideal platform and opportunity. Using forms, e-mail, etc. you can conduct surveys and get opinion of people across the world. There is hundreds of discussion groups and LISTSERVs, where one can post a question and get it answered by hundreds of people who participate in these discussions.

Internet Access

You can connect to the internet in one of two basic ways, dialing into an internet service provider's (ISP) computer, or with a direct connection to an internet service provider. The difference is mainly in the speed and cost. In most cases you connect to your ISP using a telephone line and modem. This type of connection is called dial-up connection. Sometimes you go in for a direct connection. We will see these two types of connections in a little detail.

Dial-up connection

With a dial-up account, you use your modem to convert computer bits and bytes into modulated signals that the phone lines can transmit. These signals are received by a modem at you ISP and demodulated into bits and bytes for their computer. "Modem" is short for "modulator-demodulator". You usually connect to a local ISP and can surf or browse the internet. Dial-up access is either by a way of SLIP (serial line internet protocol) or PPP (point to point protocol). To establish a conventional dial-up connection to the internet, you will need the following:

1. An account with an internet access provider. The account can be either TCP/IP or Shell.\
2. A telephone connection.
3. A computer with serial port (for external modems) or an expansion slot (for internal modems).
4. A modem (external/internal).
5. A communication (or terminal emulation) software .SLIP/PPP(TCP/IP) account holders will require browsers software (Internet Explorer,firefox,opera,etc).and e-mail software (Microsoft Outlook ,Opera Mail ,Eudora ,Thunderbird ,etc ).for shell account holders the browser software (lynx)and the E-mail software (pine) are usually available with the internet  Access.

Direct connection

You can also get a direct connection to your ISP, where you have a fixed cable or a dedicated phone line to the ISP. The most popular high speed internet access these days is ADSL. Asymmetric digital subscriber line (ADSL) is a data communications technology that enables faster data transmission over copper telephone lines than conventional voice band modem can provide. It does this by utilizing frequencies that are not used by a voice telephone call. A splitter or microfilter allows a single telephone connection to be used for both ADSL service and voice calls at the same time. Because phone lines vary in quality and were not originally engineered with DSL in mind, it can generally only be used over short distances, typically less than 4 km.

Another type of dedicated connection is an ISDN (integrated services network) line which is a higher-speed version of the standard phone line, but actually requires two phone lines. ISDN can handle more than 56,600 bps. ISDN lines scale upward, meaning you can transparently add more line to get faster speeds with a single ISDN connection, up to about 1.25 million bps. With the introduction and growing popularity of ADSL broadband technology with static IPs, the use of ISDN became less. But ISDN still plays a very big role as a backup network for point-to-point leased line customers and low cost reliable data network for governmental agencies and organizations such as banks and other financial institutions.

You can also get a dedicated line called a T1 or T3. A T1 line can handle 1.5 Mbps. A T3 line can handle 30 times that speed (45 Mbps). If you have a network in the office and several people need to access the Internet simultaneously, consider ADSL or T1 connection when a user connects to the Internet, the router automatically handles the connection. Even multiple tasks at the same time are possible and you need not have a modem or telephone line for each computer and user.

Internet Basics

For most people who are to the Internet, the first experience is quite overwhelming. Faced with the wide range of features and options and the scope, magnitude and amount of information and other resources, newbies spend a lot of time simply finding their bearings. However as one gets the feel of the internet, it becomes clear that internet is similar to any other medium of information and communication.

Once you know the information that you want to find, how to dint it, where to find it and how to access it, the internet becomes an extremely powerful resource-irrespective of whether you are using it for work, education, entertainment or just for the fun of exploring. Once you know how to send and receive electronic mail, subscribe to mailing lists, join and participate in discussion groups and internet chats, your power to communicate with people anywhere in the world will increase dramatically. The beauty of internet is that all these power and resources are available at a very minimal cost. So internet literacy is a must for every individual who wants to succeed in this information age.

Internet Protocols

We will examine the various internet protocols used. The most commonly used protocols are:

ü      Transmission control protocol/internet protocol (TCP/IP)

ü      File transfer protocol (FTP)

ü      Hyper text transfer protocol (HTTP)

ü      Telnet

ü      Gopher

ü      Wide area information service (WAIS)

Transmission control protocol/internet protocol (TCP/IP)

TCP/IP stands for transmission control protocol/internet protocol. TCP/IP is actually a collection of protocols, or rules, that govern the way data travels from one machine to another across networks. The internet is based on TCP/IP. TCP/IP has two major components: TCP and IP. The IP component does the following:

§         Envelopes and address the data

§         Enables the network to read the envelop and forward the data to its destination

§         Defines how much data can fit in a single "envelope" (a packet).

The TCP component does the following:

§         Breaks data up into packets that the network ca handle efficiently

§         Verifies whether all the packets have arrived at their destination

§         "reassembles" the data.

File transfer Protocol (FTP):

FTP stands for file transfer protocol, and is part of the TCP/IP protocol suite. It is the protocol, or set of rules, which enables files to be transferred between computers. FTP is a powerful tool which allows files to be transferred from "Computer A" to "Computer B", or vice versa.

FTP works on the client/server principle. A client program enables the user to interact with a server in order to access information and service on the server computer. Files that can be transferred are stored on computers called FTP servers. To access these files, an FTP client program is used. This is an interface that allows the user to locate the files(s) to be transferred and initiate the transfer process.

The basic steps to use FTP are:

1. Connect to the FTP server
2. Navigate the file structure to find he file you want
3. Transfer the file.

To specifies of each step will vary, depending on the client program being used and the type of internet connection. Anonymous FTP allows a user to access a wealth of publicly available information. No special account or password is needed. However, an anonymous FTP site will sometimes ask users to login with the name "anonymous" and use their electronic mail address as the password. There are a vide variety of files that are publicly available through anonymous FTP:

Ø      Shareware- Software that you can try fro free for a limited period and if you want the product you will have to buy it.

Ø      Freeware- Completely free software, for example fonts, clipart and games.

Ø      Upgrades and Patches- Upgrades to current software and "fixes" for software problems.

Ø      Documents- Examples includes research papers, articles and internet documentation.

Files on FTP servers are often compressed. Compression decreases file size. This enables more files to be stored on the server and makes file transfer times shorter. In order to use a compressed file it needs to be decompressed using appropriate software. It is a good idea to have current virus checking software on the computer before files are transferred to it.

Hypertext Transfer Protocol (HTTP):

HTTP is short for Hypertext Transfer Protocol. It is the set of rules, or protocol that govern the transfer of hypertext between tow or more computers. The World Wide Web encompasses the universe of information that is available via HTTP.

Hypertext is text that is specially coded using a standard system called Hypertext Markup Language. The HTML codes are used to create links. These links can be textual or graphic, and when licked on, can "link" the user to another resource such as other HTML documents, ext files, graphics, animation and sound. HTTP is based on the client/server principle. HTTP allows computer 1 which is client in order to establish a connection with the another computer 2 that server and make a request. The server accepts the connection initiated by the client and sends back a response. An HTTP request identifies the resource that the client is interested in and tells the server what action to take on the resource.

When a user selects a hypertext link, the client program on their computer uses HTTP to contact the server, identify a resource, and ask the server to respond with an action. The server accepts the request, and then uses HTTP respond to or perform the action. Usually hypertext links will be blue in color and will be underlined. When you move the mouse pointer over a hypertext link the pointer changes its shape to that of a hand. In the case of text based browsers, the hypertext links will be highlighted and you can navigate between them using he keyboard.

Telnet:

telnet is a protocol, or set of rules, that enables one computer to connect to another computer. This process is also referred to as remote login. The user's computer, which initiates the connection, is referred to as the local computer, and machine being connected to, which accepts the connection, is referred to as the remote, or host, computer. The remote computer can be physically located in the next room, the next town, or in another country. Once connected, the user's computer emulates the remote computer. When the user types in commands, they are executed on the remote computer. The user's monitor displays what is taking place on the remote computer during the telnet session.

The procedure for connecting to a remote computer will depend on how you internet access is set up. Once a connection to a remote computer is made, instructions or menus may appear. Some remote may resources, such as library catalogs, are available via telnet without an account and password. Telnet also operates on the client/server principle. The local computer uses a telnet client host, computer uses a telnet server program to accept the connection and send responses to requests for information back to the local computer. Telnet allows the user to access internet resources on other computers around the world. A variety of resources are available through telnet. For example: library catalogs, database, other internet tools such as FTP, Gopher and WWW etc.

Gopher

Gopher is a protocol designed to search, retrieve, and display documents from remote sites on the internet. In addition to document display, document retrieval, it is possible to initiate on-line connections with other systems via Gopher. It accomplishes this using the client/server model of users running client software on their local machines that provide an interface that interacts with remote servers or computers that have information of interest.

Gopher was created as a piece of software to utilize some of he services that were becoming available on the internet. It was designed to work with a variety of different internet stand alone services. The integration of many services into Gopher has made the internet an easier medium to navigate. Gopher can work with the following internet tools, or systems like WAIS, FTP, HTTP, etc.

The World Wide Web was in its infancy in 1991, and Gopher services quickly became established.

• Gopher client functionality was quickly duplicated by early web browsers, such as mosaic. Furthermore, the user friendliness of the world wide web, with its integration of text and graphics, made gopher less appealing.
• Gopher has an inflexible structure when compared to the free form HTML of the web. With gopher, every document has a defined format and type, and the typical user must navigate through a single server defined menu system to get to a particular document.

WAIS

WAIS stands for Wide Area Information Service. WAIS is an internet search tool that is based on the Z39.50 standard. The Z39.50 standard describes a protocol, or set of rules, for computer-to-computer information retrieval. WAIS also works on the client/server principle. A WAIS client program enables the user's computer to contact a WAIS server, submit a search query, and receive a response to that query. WAIS has the capability of simultaneously searching in more than one database. After the search phrase has been typed into the client interface, the user can then choose which database should be sued to complete the search. Depending on the WAIS client software being used, this may be a matter of using a mouse to select database names displayed on a screen, or of typing in the database using the keyboard. To understand how WAIS works to complete a search, it is important to know that the database itself is not being searched for the requested search phrase. Rather, an index for the database is searched. The index is created by people, and can contain all, or as many, of the words in all the items contained in the database. Once the search has been executed, all items containing he words appearing in the search phrase will be returned to the user, provided that the words in the search phrase appear in the indexes of the selected databases. Because of the abundance of content and search engines now available on the Web, few if any WAIS servers remain in operation.

Internet Addressing:

In general, internet addressing is a systematic way to identify people, computers and internet resources. On the internet, the term address is used loosely. Address can mean many different things from an electronic mail address to a URL.

IP Address:

If you want to connect to another computer, send an e-mail message, or transfer files to or from another computer, you first need to know where the other computer is you need the computer's address. An IP address is an identifier for a particular machine on a particular network; it is part of a scheme to identify computers on the internet. IP addresses are also referred to as IP number and internet addresses. An IP address consists of fur section separated by periods. Each section contains a umber ranging from 0 to 255. Example 202.54.1.6. These four sections represent both the machines itself, or host, and the network that the host is on. The network portion of the IP address is allocated to internet service provides by the interNIC, under authority of the internet assigned numbers authority. ISPs then assign the host portion of the IP address to the machines on the networks that they operate. The IP addresses have the following characteristics in common

• IP address are unique.
• No two machines can have the same IP number.
• IP addresses are also global and standardized.
• All machines connected to the internet agree to user the same scheme for establishing an address.

Domain Names:

A domain name is a way to identify and locate computers connected to the internet. No two organizations can have the same domain name. A domain name always contains two or more components separated by periods, called "dots". Some examples of domain name are: www.depth-of-knowledge.blogspot.com ,etc. The last portion of the domain name is the top-level domain name and describes the type of organization holding that name. The major categories for top-level domain names are:

• Com
• Edu
• Biz
• Mobi
• Name
• Net
• Org
• Tel
• Int