The internet is a network of networks. Millions of computers all over the world are connected through the internet. Computer users on the internet can contact one another anywhere in the world. If your computer is connected to the internet, you can connect to millions of computers. You can gather information and distribute your data. It is very similar to the telephone connection where you can talk with anyone anywhere in the world.

On the Internet, a huge information resource is accessible to people worldwide. Information in every field from education, science, health, medicine, history, and geography to business, news, etc. can be retrieved through the internet. You can also download programs and software packages from anywhere in the world. Due to the tremendous information resources the Internet can provide, it is now indispensable to every organization.

Origin of the Internet:

In 1969 Department of Defense(DOD) of the USA started a network called ARPANET(Advanced Research Projects Administration Network) with one computer in California and three in Utah. Around 1980, NSFNET(National Science Foundation Network) was created. With the advancement of modern communication facilities, other computers were also allowed to be linked up with any computer of NSFNET. By 1990 many computers were looking up to NSFNET giving birth to the internet.

How Internet Functions:

The Internet is not a governmental organization. The ultimate authority of the Internet is the Internet Society. This is a voluntary membership organization whose purpose is to promote global information exchange. The Internet has more than one million computers attached to it.

Basic elements of networking:

The following are the basic requirements for working on a communication system.

1. A sender(source) creates the message to be transmitted.
2. A medium that carries the message.
3. A receive (sink) which receives the message.

In data communication, four basic terms are frequently used. They are…

• Data: A collection of facts in raw forms that become information after processing.
• Signals: Electric or electromagnetic encoding of data.
• Signaling: Propagation of signals across a communication medium.
• Transmission: Communication of data achieved by the processing of signals.

Communication Protocols:

You may be wondering how do the computers send and receive data across a communication link. The answer is data communication software. The data communication software instructs computer systems and devices as to how exactly data is to be transferred from one place to another. The procedure of data transformation in the form of software is commonly called the protocol.

The data transmission software or protocols performs the following functions for the efficient and error-free transmission of data.

1. Data sequencing: A long message to be transmitted is broken into smaller packets of fixed size for error-free data transmission.
2. Data Routing: It is the process of finding the most efficient route between source and destination before sending the data.
3. Flow Control: All machines are not equally efficient in terms of speed. Hence the flow control regulates the process of sending data between fast sender and slow receiver.
4. Error Control: Error detecting and recovering is one of the main functions of communication software. It ensures that data are transmitted without any error.

Data Transmission Modes:

There are ways to transmit data from one point to another.

1. Simplex: In simplex mode, the communication can take place in one direction. The receiver receives the signal from the transmitting device. It is rarely used for data communication.
2. Half-Duplex: In half-duplex mode, the communication channel is used in both directions, but only in one direction at a time. thus a half-duplex line can alternately send and receive data.
3. Full-duplex: In full duplex, the communication channel is used in both directions at the same time. This is the more efficient mode. An example of this mode of transmission is the telephone line.

Some Terminologies of the Internet:

WWW:

The World Wide Web is a huge set of interlinked documents, images, and other resources, linked by hyperlinks and URLs. These hyperlinks and URLs allow the web servers and other machines that store originals, and cached copies of, these resources to deliver them as required using HTTP(Hypertext Transfer Protocol). HTTP is only one of the communication protocols used on the Internet.

URL(Uniform Resource Locator):

URL is a type of Uniform Resource Identifier(URI) that specifies where an identified resource is available and the mechanism for retrieving it.

Abbreviation of Uniform Resources Locator, the global address of documents and other resources on the World Wide Web is the unique address for a file that is accessible on the Internet.

E-mail:

E-mail stands for Electronic Mai. This is one of the most widely used features of the Internet. Mails are regularly used today where with the help of postage stamps we can transfer mail anywhere in the world. With electronic mail the service is similar. But here data are transmitted through the Internet and therefore within minutes the message reaches the destination may it be anywhere in the world. Therefore the mailing system is excessively fast and is being used widely for mail transfer.

Search Engine:

Search engine is a tool designed to search for information on the World Wide Web. The search results are usually presented in a list and are commonly called hits. The information may consist of web pages, images, information, and other types of files. Example- Yahoo, Google, etc.

ISP:

An Internet service provider (ISP, also called Internet access provider or IAP) is a company that offers its customers access to the Internet. The ISP connects to its customers using a data transmission technology appropriate for delivering Internet protocol datagrams, such as dial-up, DSL, cable modern, or dedicated high-speed interconnects. Example- VSNL(Videsh Sanchar Nigam Limited), Satyam, etc.

DNS:

The Domain Name System(DNS) is a naming system for computers, services, or any resources participating in the Internet. It associates various information with domain names assigned to such participants. An often-used analogy to explain the Domain Name System is that it serves as the “phone book” for the Internet by translating human-friendly computer hostnames into IP addresses. For example, www.example.com translates to 208.77.188.166.

HTTP(Hypertext Transfer Protocol):

HTTP is an application-level protocol for distributed, collaborative, hypermedia information systems. Its use for retrieving interlinked resources led to the establishment of the World Wide Web.

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