Makhan Lal Chaturvedi MCU | DCA & PGDCA English Notes : Second Sem Unit 1 Internet & E-commerce
Unit -1
1. Introduction to Internet
The Internet is a global communication system that connects thousands of individual networks together. It allows the exchange of information between two or more computers on a network. Thus the Internet helps in transferring messages through mail, chat, video and audio conferences, etc. It has become indispensable for day-to-day activities such as bill payments, online shopping and surfing, conducting online classes, doing online work, communicating with peers, etc. The Internet is defined as the information super highway for accessing information from the web. However, it can be defined in many ways-
• The Internet is a worldwide global system of interconnected computer networks.
• The Internet uses the standard Internet Protocol (TCP/IP).
• Each computer on the Internet is identified by a unique IP address
• An IP address is a unique set of numbers (such as 110.22.33.114) that identifies a computer location.
• To assign names to IP addresses a special computer DNS (Domain Name Server) is used so that the user can locate a computer by a name.
• For example, a DNS server refers the name https://www.kamaldhakad.com or https://www.onlinetyari.in to a particular IP address on which this website is hosted.
• The Internet is accessible to every user all over the world.
1. 1 Evolution of Internet
Today the whole world is in the grip of the Internet, it seems as if life cannot be imagined without the Internet. Today everyone has become addicted to the Internet, because the things that could not even be imagined, have been turned into reality by the Internet. Today, through the Internet, one can talk to a person sitting in any corner of the world while sitting at home. One can send messages through email or social networking sites, make video calls, while the Internet has made communication so easy that the economy of the country and the world has become much better than before. The Internet was first started by the US Army in the Pentagon, the Defense Department of America. In the year 1969, a Networking Project named ARPANET i.e. Advance Research Project Agency was launched and many of the following technical and infrastructure changes have been made in it:
• The origin of the Internet developed from the concept of Advanced Research Project Agency Network (ARPANET).
• ARPANET was developed by the United States Department of Defense.
• The original purpose of ARPANET was to provide communication between various bodies of the government.
• Initially there were only four nodes, formally called hosts.
• In 1972 ARPANET was located in 23 different countries and thus came to be known as the Internet.
• With the invention of new technologies by that time such as TCP/IP protocols, DNS, WWW, browsers, scripting languages, etc. the Internet provided a medium to publish and access information on the web.
2. World Wide Web (WWW)
WWW means World Wide Web. All the resources and users on the Internet who are using hypertext or hypertext links, this technology is called www. World Wide Web is a system by which each website is given a special name. It is identified on the web by the same name. www was first used by TIM BERNERS LEE in 1989 in the CERN laboratory. In the World Wide Web, information is kept in the form of websites. These websites are stored as hypertext files on the web server. The World Wide Web is a universe of network-accessible information, an embodiment of human knowledge. In simple words, the World Wide Web is a way of exchanging information between computers on the Internet, binding them together into a vast collection of interconnected multimedia resources.
2.1 Evolution of WWW
The World Wide Web was created in 1989 by Timothy Berners-Lee at CERN, Geneva. The World Wide Web came into being as a proposal by him so that researchers at CERN, Geneva could efficiently work together on the advancement of the World Wide Web. The hard work of the researchers resulted in the World Wide Web. The following diagram briefly defines the evolution of the World Wide Web:
3. Advantages of the Internet
The Internet covers almost every aspect of life that one can think of. Here we will discuss the following advantages of the Internet:
The Internet allows us to communicate with people sitting at remote locations. There are various applications available on the web that use the Internet as a medium for communication. One can find various social networking sites which are as follows-
• Yahoo
• Google+
• Flickr
One can surf the internet for any kind of information. Information about various subjects like technology, health and science, social studies, geographical information, information technology, products etc. can be searched with the help of search engines. Apart from being a source of communication and information, the internet is also a medium of entertainment. Following are the various ways to entertain on the internet-
• Online television
• Online games
• Songs
• Videos
• Social networking apps
• Internet allows us to use many services like-
• Internet banking
• Matrimonial services
• Online shopping
• Online ticket booking
• Online bill payments
• Data sharing
• Internet provides the concept of electronic commerce, whereby business deals can be made on electronic systems.
3.1 Disadvantages of Internet
The Internet has proved to be a powerful source of information in almost every field but the following disadvantages exist in the Internet –
• There is always a possibility of losing personal information like name, address, credit card number, so one should be very careful while sharing such information. One should use credit cards only through certified sites.
• Another disadvantage of the Internet is spamming. Sending repeated messages on the same topic to a person is called spamming i.e. sending unwanted messages or advertisements to people is called spamming. The main purpose of spamming is to steal data from the user’s computer. In this, problems like promotional emails are also faced. These emails work without any purpose and create obstacles in the entire system.
• Viruses can be easily spread in computers connected to the Internet. Your system may crash or your important data may get deleted due to such virus attack.
• Also, the biggest danger on the Internet is pornography. There are many pornographic sites which let children use the internet but indirectly affect the healthy mental life of children.
• Various web sites which do not provide authenticated information lead to misunderstanding among many people.
4. Internet
It is a worldwide/global system of interconnected computer networks. It uses the standard Internet Protocol (TCP/IP). Each computer on the Internet is identified by a unique IP address. The IP address is a unique set of numbers (e.g. 110.22.33.114) which identifies the location of the computer. A special computer DNS (Domain Name Server) is used to assign a name to the IP address so that the user can locate the computer by a name. For example a DNS server refers the name https://www.mcu.ac.in to a particular IP address on which this website is hosted.
4.1 Intranet
Intranet is a system in which many PCs are connected to each other. The PCs in the intranet are not available to the world outside the intranet. Usually each organization has its own intranet network and only the members/employees of that organization can use the computers in its intranet. Each computer in the intranet is also identified by an IP address which is unique among the computers in the intranet.
4.2 Similarities between Internet and Intranet
• Intranet uses internet protocols like TCP/IP and FTP.
• Intranet sites are accessible through web browsers in the same way as websites in the internet. However, only members of the intranet network can access intranet hosted sites.
• Intranet has its own instant messenger to be used similar to Yahoo Messenger/Google Talk on the internet.
4. 3 Difference Between Internet and Intranet
The Internet is common to PCs worldwide while the Intranet is specific to a few PCs.
The Internet provides a wider and better access to websites for a large population, while the Intranet is restricted.
The Internet is not as secure as the Intranet. Intranets can be securely privatized as per the need.
5. Internet Service Provider (ISP)
An Internet service provider is a company or organization that provides Internet connection services and other related services. Most telephone companies are Internet service providers. They provide services such as Internet, domain name registration and hosting. ISPs have both domestic and international networks so that the user can connect to the global network through the connection provided by the customer ISP. The network streams data through wired (modem, leased line and broadband), radio etc. network transmission mediums.
5.1 Function of Internet Service Provider (ISP)
The function of an Internet Service Provider is to provide Internet service to people who need Internet service. Internet service providers can provide dial-up or broadband service to consumers. The most common method is through telephone lines. Dial-up connections require the use of a phone line and typically dial-up connections provide a connection speed of 56 KBS or less.
Broadband connections can be ISDN, broadband wireless access, cable modem, DSL, satellite or Ethernet. Broadband varies in speed between 64 KB and 20+MB per second. All ISPs have their own servers and users are connected to those servers.
6. Dial Up Connection
A dial-up connection uses a modem to access the Internet. The modem connects the computer to standard phone lines, which serve as the data transfer medium. A dial-up connection is established when two or more communication devices use a public switched telephone network (PSTN) to connect to an Internet service provider (ISP). When a user initiates a dial-up connection, the modem dials a phone number of the Internet service provider (ISP) that is designated to receive dial-up calls. The ISP then establishes the connection, which usually takes about ten seconds and several beeping sounds.
Once the dial-up connection is established it remains active until the user disconnects from the ISP. This is usually done by selecting a “disconnect” option using the ISP’s software or a modem utility program. If the dial-up connection is interrupted by an incoming phone call or if someone at home answers the phone, the service may also be disconnected. Many remote areas rely on dial-up connections for Internet because providing broadband and cable Internet access in remote areas with low population is a difficult task. Dial-up connection is a cheap Internet connection to access the Internet, but the speed of dial-up connection is slow.
7. Leased line connection
A permanent telephone connection between two points established by a telecom common carrier is called a leased line connection. Typically, leased lines are used by businesses to connect geographically distant offices. Unlike a normal dial-up connection, a leased line is always active. The charge for the connection is a fixed monthly rate. The monthly charges of a leased line depend on the distance between the two points and the speed of the circuit as the connection does not carry anyone else’s communication and maintains the carrier’s quality level to ensure high speed internet connection.
For example, a T-1 channel is a type of leased line that provides a maximum broadcast speed of 1.544 Mbps. You can split the connection into separate lines for data and voice communication or use the channel for a single high speed data circuit. Splitting the connection is called multiplexing. Leased lines are being used by companies and even individuals for internet access as they afford faster data transfer rates if the internet is heavily used.
8. VSAT (Very Small Aperture Terminal)
Very Small Aperture Terminal (VSAT) is technology commonly referred to as a private earth station. The earth station is designed to transmit and receive data signals via satellite signals. VSAT includes the term “very small” which refers to the size of the antenna on the VSAT dish.
The antenna is usually about four feet in diameter and consists of a low noise converter, which receives signals from the satellite, and a block up converter (BUC) which transmits the signals to radio waves. The antenna can be deployed on the ground or it can be mounted on a rooftop.
VSAT is designed to serve both businesses and individuals and involves the use of specific technology and equipment designed to facilitate effective telecommunications and Internet connectivity. A VSAT connection is established through the use of an antenna system and your PC or mobile device communicates with the antenna and then the antenna uses transceiver components to send and receive signals from the satellite. It is used in marine areas and remote land areas.
9. Uniform Resource Locator (URL)
A Uniform Resource Locator (URL) is the address of a resource on the Internet and the protocol used to access the Internet. Just like a home address indicates the location of a person, a URL indicates the location of a web resource, so URLs are often called web addresses.
A URL contains the following information:
• The protocol used to access the resource.
• The location of the server (by IP address or domain name).
• The port number on the server (optional).
• The location of the resource in the server’s directory structure.
• A fragment identifier (optional).
9.1 Components of URL
World Wide Web
Top Level Domain / Domain Extension Indicates the type of site like edu, gov, Commercial
https://www.kamaldhakad.com & https://www.kamaldhakad.in
Hypertext Transfer Protocol
Domain Name
Geographical Domain
Indicates the source of the website like India
10. Portal
A group of websites is called a portal. Portal literally means gateway. Portal is actually a website itself, from which many other related websites can be accessed. Many types of portals are available when connected to the Internet. Information is collected from various sources on portals and made available in an organized form. Along with this, many types of services are also provided on the portal.
For example, many portals provide search engine facility to the user, apart from this, they also provide facilities of community chat forum, home page and email. Portals have links to search engines, subject directories and other services such as news, entertainment, stock market, shopping etc. Through these links, you can reach that website. You can also see news, stock prices and gossip about movies etc. on the portal. Users can also customize many portals according to their needs. Portals are sponsored by big search engines and browser providers. All Internet service providers focus more on two services on portal sites, entertainment and information. Both these services are available to the user on the first page of the website. In simple terms, we can say that a portal is a website that provides entertainment and information services to the user and where the user gets more experience on the Internet.
The names of some popular portals are as follows-
• aol.com
• netscape.com
• yahoo.com
• excite.com
The features of portal are as follows –
• With the help of portal, information can be obtained from other websites.
• The system of registration on the portal is simple.
• Portals act as a gate to connect to the website.
• Portals provide the facility of web hosting.
• Almost all types of machines can be connected to the portal.
11. Internet Services
Internet services allow us to access huge amounts of information such as text, graphics, audio and software on the Internet. The following block diagram shows four different categories of Internet services.
• Internet Services
• Communication Services
• Information Retrieval Services
• Web Services
• World Wide Web
11. 1 Communication Services
Various types of communication services are available which facilitate the exchange of information with individuals or groups. A brief introduction of communication services is as follows:
- Electronic Mail – Used to send electronic messages over the Internet.
- Telnet – Used to log on to a remote computer which is connected to the Internet.
- News Group – Provides a forum for people to discuss topics of common interest.
11. 2 Information Retrieval Services
There are many information retrieval services which provide easy access to information available on the Internet. A brief introduction of information retrieval services is as follows:
File Transfer Protocol (FTP) – Provides the user with the facility to transfer files.
Archie – It is an updated database of public FTP sites and their contents. It helps in searching a file by its name.
Gopher – Used for searching, retrieving, and displaying documents on remote sites.
11.3 Web Services
Web services allow the exchange of information between applications on the web. Using web services, applications can easily interact with each other.
11. 4 World Wide Web (WWW)
WWW is also known as W3. It provides a way to access documents saved in many servers on the Internet. These documents can contain text, graphics, audio, video, hyperlinks. Hyperlinks allow the user to navigate between documents.
12. Applications of the Internet
In its early days, the use of the Internet was limited to scientists sharing research papers and other information with each other. But gradually the Internet developed and new technologies were added to it. Modern Internet has become a part of our lifestyle. Almost all our daily tasks are being done sitting at home through the Internet. In its beginning, the Internet was limited to sharing information only, but at present, the Internet has expanded to almost every field. From medicine to the purchase of daily use goods, the following are some of the major applications of the Internet where it is used.
12.1. Communication
We use the Internet the most to connect with each other. Through the Internet, we can send and receive messages to our loved ones anytime and anywhere quickly. One way to send messages on the Internet is email. Apart from email, we can connect with our loved ones online through social media sites like Facebook, Twitter, WhatsApp, Telegram, Instagram, etc. and can see their every activity with our own eyes.
12. 2. To search information-
The Internet was developed only so that information could be exchanged. Before today, it was never easy to get information in this way. But today we can get information from any corner of the world through the internet and that too in a few seconds. We can get news from every corner of the world on our computer while sitting at home. Search engines are used to find information on the internet.
12.3. Entertainment-
The internet is used as a means of entertainment. The options in the field of entertainment are unlimited. Through this we can watch and listen to movies, songs, videos etc. Those who are fond of reading can read their favorite author. Apart from this, the world of video games is open for us all the time for entertainment. There are millions of entertainment channels on YouTube, on which comedy, shayari, romantic videos, film dialogues, videos made by local artists, songs etc. are being uploaded daily. You can get entertainment without any charge. If you are fond of making videos yourself, then you can start your own YouTube channel for this and make and upload videos. Similarly, videos can be viewed and made on many micro video platforms.
12.4. Shopping
The business done through the internet is called e-commerce. Through the internet, the market can be viewed from home and goods can be purchased. Through this, you can buy goods of your choice by seeing many options simultaneously from home. Apart from this, information about popular fashion can also be gathered. Amazon, Flipkart, Snapdeal, Paytm Mall, Myntra, Walmart, Alibaba, eBay are some popular online shopping marketplaces.
12.5. Education
The field of e-learning is growing rapidly in the world of internet. Today, through the internet, we can choose our favorite college, school for ourselves while sitting at home. Apart from this, we can get information on our computer about which college has the course of our choice and all the information about that course such as course fees, duration of the course etc. Today the field of e-learning has developed a lot. We can study from the best teachers of the world while sitting at home and can also take advantage of the facility of studying by taking admission in the top universities of the world.
12.6. E-Governance
The Digital India program is an effort made in this direction. Under which there is an effort to make government facilities accessible to the general public in digital form. As a result, today we see that most of the government services have started becoming available online. You can take advantage of ration card, Aadhar card to pension and social security schemes.
12.7 Medicine
The internet is being used on a large scale in the field of medicine. Nowadays many pathology labs collect different types of human body samples and send them to a big lab for testing and the report is available to the patient very quickly through the website, due to which quick treatment is available according to the report. Internet is being used on a large scale for viewing information about various medicines or ordering medicines and making payment online etc.
13. E-mail (Electronic Mail)
E-mail has become an important part of the communication network of most modern offices and organizations. It is one of the best applications of computer science. The most popular email is Gmail which is operated and maintained by Google. Data and messages can be transmitted from one computer to another using telephone lines, microwave links, communication satellites or other telecommunication equipment. A single message can be sent to a large number of different addresses, which can be forwarded and replied to. Email can be sent by an organization from its own local network or further through communication networks around the world.
13.1 Function of Email
Email services usually store messages at a central location called a server from where a message can be downloaded by a receiver by logging in to his mail box. The client or receiver of the email message usually uses browser based applications like GMail, Facebook, Twitter etc. to open and login to his email box. (All these e-mail services are free, you just have to register yourself or sign up) Thus the message is delivered to the destination using telephone cables, wireless networks etc. With a subscription to a public e-mail network, a user only needs a modem and a telephone to send text or voice mail.
13.2 E-mail System
The e-mail system consists of the following three components:
• Mailer
• Mail Server
• Mailbox
13.2.1 Mailer
It is also called mail program, mail application or mail client such as Gmail, Rediffmail etc. It allows us to manage e-mail, read and compose emails.
13.2.2 Mail Server
The function of the mail server is to receive, store and deliver emails. It is necessary for the mail server to be in running state all the time because if the mail server crashes or goes down, there is a risk of emails being lost.
13.2.3 Mailbox
Mailbox is usually a folder that contains emails and information about emails. Mail follows a client server approach in its functioning. The client is the mailer i.e. mail application or mail program (e.g. Gmail, Rediffmail) and the server is a device that manages emails. The following examples will describe the basic steps involved in sending and receiving emails and provide you a better understanding of the working of an email system:
• Suppose a person named A wants to send an email message to a person named B.
• Person A composes the message using the mailer program i.e. mail client and then sends the message by selecting the send option. The message sent by person A reaches the mail server of person B with the help of Simple Mail Transfer Protocol.
• The mail server stores the email message on disk in the area specified for person B.
14. Internet Protocol
IP stands for “Internet Protocol”. IP provides a standard set of rules for sending and receiving data over the Internet. It allows devices running on different platforms to communicate with each other as long as they are connected to the Internet.
An Internet-connected host must have an IP address (IPv4 or IPv6) to be recognized by other devices.
15. FTP File Transfer Protocol (FTP)
FTP is called File Transfer Protocol. FTP is a standard Internet protocol provided by TCP/IP that is used to transfer files from one host to another. It is mainly used to transfer web page files from their creator to a computer that acts as a server for other computers on the Internet.
16 Domain Name System (DNS)
The Domain Name System (DNS) is the phonebook of the Internet. Users access information online through domain names such as google.com or mcu.ac.in. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names into IP addresses so that browsers can load resources on the Internet.
Each device connected to the Internet has a unique IP address that other machines use to locate a device. DNS servers eliminate the need for a user to remember IP addresses such as 192.168.1.1 (in IPv4).
216.3.128.12 kamaldhakad.com
17. TCP / IP
TCP means Transmission Control Protocol and IP means Internet Protocol. This is a set of rules that decide how the Internet works. It makes information transfer and communication possible between two computers. They are used to send data securely. The role of TCP is to divide the data into small packets and the role of IP is to mark the address of the destination on these packets.
TCP / IP are protocols available in the Internet. Through which information is exchanged between the Internet, network or other Internet devices. TCP / IP are a group of protocols that create communication between computers and networks. Through which we can exchange information with the Internet with the help of our mobile and other devices.
18. UDP (User Datagram Protocol)
UDP is a communication protocol used on the Internet, especially where time sensitivity has to be taken care of in transmission such as video playback or DNS lookup etc. It speeds up communication because handshakes are not necessary in the UDP protocol and data is transferred without the permission of the receiving party, so it allows the protocol to operate very quickly. There is also a fear of receiving unnecessary data which you do not want to receive.
A TCP connection (which is commonly used to load web page content) requires a handshake in which the receiver agrees to the communication before data is sent. UDP sends data without confirmation and sometimes such a request becomes a cause of fraud.
19 HTTP
HTTP means Hypertext Transfer Protocol. HTTP is the protocol used by the World Wide Web and this protocol defines how messages are formatted and transmitted, and what actions the web server and browser should take in response to various commands.
For example, when you enter a URL in your browser, it actually sends an HTTP command to the web server and directs it to fetch the requested web page and load it on the web.
20 Telnet
Telnet is an old internet facility that allows you to login to a remote computer. In other words, it allows you to access a remote computer while sitting at your computer. This is also called remote login. Usually a Telnet program gives you a text based window for another computer. You are given a login prompt for that system. If you have permission to access the system, you can perform tasks on it just like you would on your computer. This facility is very useful for those people who want to do such work on other computers, which cannot be done through other facilities like FTP etc. It is clear that this facility is not for everyone. It is given only to authorized people and every Telnet computer has its own rules for giving such permission to external users. Telnet is an application layer protocol. It is used for bi-directional interactive text oriented communication in Internet and local area network. For this it uses virtual terminal connection. It was developed in 1969 and it was given standard by Internet Engineering Task Force due to which it became the first Internet standard.
21 Internet Chatting
Chat refers to the process of communicating, interacting or exchanging messages over the Internet. It involves two or more individuals who communicate through chat-enabled services or software. Chat is also known as chatting, online chat or Internet chat. Chat can be done via text, verbal, audio, visual or audio-visual (A/V) communication via the Internet. If conducted via a desktop, chat requires software that uses Internet Relay Chat (IRC) or an instant messenger application, where a central server manages the chat communication between different users.
21. 1 Text Chatting
Text chatting is communication done by entering text in real time between two users via a computer. Once the chat starts, the first user enters text by typing on the keyboard and the entered text appears on the second user’s monitor. Most networks and online services provide a chat facility.
21.2 Voice Chat
This is a modern form of chat, in which two users are connected to each other through voice. Speakers are required to receive sound and microphone is used to talk. If the internet speed is low, then the sound comes intermittently. In this, the charge for talking does not depend on time but depends on the amount of data transferred.
22 Web Server
Web server is a computer where web content is stored. It is a computer program that delivers web pages. The basic purpose of a web server is to store, process and deliver web pages to the user. Web servers use Hypertext Transfer Protocol (HTTP) for intercommunication. These web pages are mostly static content which includes HTML documents, images, style sheets, text etc. Apart from HTTP, a web server uses SMTP (Simple Mail Transfer Protocol) and FTP (File Transfer Protocol) for email and file transfer and to store web content.
The main job of a web server is to display the content of a website. If a web server is not exposed to all users and is used internally, it is called an intranet server. When a web browser (such as Chrome or Firefox) requests a website with a URL or web address bar (such as www.kamaldhakad.com), the browser sends a request to the Internet for the corresponding web page. A domain name server (DNS) converts this URL into an IP address (for example 192.168.216.345), which points to a web server.
23. Web Hosting
When you create a website or blog, its contents such as images, video pages, etc. have to be stored on the server so that other users can access that content through the Internet. Web hosting is a type of service that provides us the facility to upload our website on the Internet.
For website hosting, we need a powerful server which should always be connected to the Internet so that our website can be available to the user 24 hours a day without any problem.
We cannot maintain this type of server ourselves because the cost of its maintenance is very high. Therefore, we take the help of web hosting companies for website hosting. Web hosting companies have their own powerful servers, technology and staff with technical expertise.
We buy hosting service from them on a monthly or annual package and we get space in their server where we can easily host our website.
24 Web Publishing
In simple words, publishing any information or content on the Internet is called web publishing or online publishing. Some of the following tasks are done in it:
• Creating and uploading a website.
• Updating a web page.
• Publishing blog posts etc.
The content to be published can be in many different formats like text, images, videos, PDFs etc. It is important to note here that publishing content on social media like Facebook, Twitter etc. is not called web publishing.
24.1 Steps of web publishing-
After designing a website, the process of uploading it on the internet is completed in several steps, we can divide this entire process into the following 5 steps-
1. Registration of domain name.
2. Web hosting.
3. Website design and development.
4. Promotion.
5. Maintenance.
25 Domain Name Registration.
You can use a word or phrase as a domain name. If the domain is for a company, you can put your company’s name in the domain, making it easier for your customers to find you on the Internet.
Although a long domain is harder to remember, it can contain more keywords, which is important because some search engines use keywords in a domain name as part of the search algorithm.
After creating a website, the site needs its own domain name to ensure its presence on the Internet. Users use this domain name to find the products and services available by you on the Internet. For example, you can get all the information about the university on https://mcu.ac.in.
We can get the domain name registered through many different companies. Such companies that register the domain name are called ‘domain registrars’. The registration of the domain name is mainly done through the same companies on whose host server you upload your website. But in the past few years, this system has changed, now you can choose different companies to register domain and buy web space.
The following are the names of some popular domain registrars.
• GoDaddy
• NameCheap
• ResellerClub Netfirms
When we register our domain with the help of a domain registrar, it provides us the domain control panel and its user name, password in exchange for a certain amount. With the help of this user name and password, we can login to the domain control panel and link the name server given by the web space provider with the domain. This is a very important task to start a website.