Effects of Internet

Positive & Negative Effect of Internet

The Internet is greatly affecting our society. These affects are both positive and negative. Following are some important effects of the Internet on the society:

Positive Effects

The positive effects of the Internet of the society are as follows:

• Globalization

Internet has converted this world into a global village. People are connected with one another using the Internet and related technologies. It has provided more opportunities of interaction. It also enables people to understand the views of one another.

• Flow of Information

Internet contains information on all types of topics. People can search information on any topic. Search engines are used to search information on Internet. Easy access to information has enabled people to be informed.

• Better Understanding

Internet is an easy way of communication among people. They can exchange their views. It has created better understanding. People can understand the views and thinking of one another. It helps in creating harmony and peace in the world.

• Comfort in Life

The use of Internet has provided many comforts for society. People can perform their duties easily. They can sell and buy sell and buy sell and buy goods online. They can run their business using Internet.

• Knowledge

Internet is a source of huge information. People can get information from websites. They can interact with different people, scholars and learned persons to get knowledge.

Negative Effects

Some negative effects of Internet on the society are as follows:

• Social Cutoff

Many people spend a lot of time on the Internet. It affects the social interaction with the people. 

• Immorality

Internet contains many immoral websites. The websites contains such material that is against the moral values of society. These websites damage the character of young people.

• Wastage of Time

Many people use Internet without any positive purpose. The young people waste their time n chatting. It affect their performance and makes them inefficient.

News Group

News Groups.

A newsgroup is a discussion group on the Internet. People exchange information on a vast range of topics such as news, business, science and computer. A user sends message to the newsgroup to participate in discussion. Other users in the newsgroup read and reply to the message.

A software is required to obtain articles from news server. A news server is a host computer that exchanges articles with other server on the Internet. These servers use Network News Transfer Protocol (NNTP) to communicate. The users have to subscribe on a news group to view articles on a specific topic.

Search Engine

What is search engine?

Search engine is a website that provides the facility to find the required websites on a particular topic. A user can search any topic on Internet using search engines. Internet contains a lot of information. A large number of websites about different topics are available. A user cannot remember all websites. He can search different websites using search engines.

Search engines contains the record of many websites. It searches the required websites and display them to the user. Search engines are very powerful tools for finding information.

Searching Information using Search Engine.

Keywords are used to search the required information from search engine. Keyword is a word or set of words that is related to the topic being searched. The keyword is typed in double quotation if it consists of two or more words.

For example, the following keywords can be used to search information about Pakistan universities:

“Pakistani Universities”                                  Universities in Pakistan”

Most Popular Search Engines are followings:

Google                        http://www.google.com

Yahoo                         http://www.yahoo.com

Infoseek                      http://www.infoseek.com

Lycos                          http://www.lycos.com

Altavista                     http://www.altavista.digital.com

Netscape                     http://www.netscape.com

Bing                            http://www.bing.com

Ask                             http://www.ask.com

Excite                         http://www.excite.com

URL & Website

Different between URL & Website

URL: URL stand for Uniform Resource Locator. The URL is the web address for any given web document. Every web document has a unique URL.

Website: A collection of related web pages is called website. Each website has a unique web address. It contain text, graphics sound and video etc.

ISP

ISP

ISP stands for internet service provider. It is a company that provides internet connections. ISP also provides the facilities of email. Different ISPs in Pakistan are  PTCL, Word Call, Comsats.

Disadvantage of email

Disadvantage of Email

These are following

• Junk Email:

Junk email is unwanted email. It is also known as spam. A person may send such email that the receiver does not want to read. A large number of junk emails may fill the space of email account.

• Possible Delay:

Email is read when the user connects to the internet and checks email account. An urgent message may be ignored or delayed if a person does not check his email account soon.

• Lack of Privacy:

Email does not provide high privacy. An email passes from one computer system to another through different networks. The system administrator of junk emails or a hacker can read the contents of emails.

• No Emotions:

An email message cannot express emotions properly. The receiver cannot view the facial expression or voice of the sender.

• Spreading of Virus:

Most of the viruses are spread through email messages. Virus can spread if the user opens an email containing a virus.

• Communication Problems:

Email may not be delivered successfully due to communication errors.

Email

Write the note an Email

Email:

Email stands for Electronic Mail. Email is the exchange of messages and files through Internet. Message can be in the form of graphics, sounds, video clips or simple text. It is a fast way of sending messages anywhere in the world in a very short time.

The sender and receiver may be sitting in the same building or anywhere in the world. One email message can be sent to multiple recipients. Email facility is provided by many internet Service providers or specialized websites. Yahoo, Hotmail and Gmail are some popular examples of email providing websites.

Working of Email:

An email program is used to create, send and receive emails. It is also known as email client. When the user sends an email message, the computer connect to an email server and transmits a copy of the message to that server. Email server is a host computer on the internet that is used to send and receive emails. The email server receives the message and finds out the email server where that email is to be sent. It connects to that server and transmits another copy of the message.

Email Attachment:

An email message can also contain attachments. Attachment is a process of sending connecting  files with email message. Any type of file can be attached to email such as documents, spreadsheets, audio and video etc. MIME is an internet protocol that supports email attachments. It stands for Multipurpose Internet Mail Extension. Different websites provides different file size that can be attached with an email message. Yahoo provides attachment size of 10MB.

URL

Define URL? 

URL stands for Uniform Resource Locator. The URL is the web address for any given web document. Every web document has a unique URL. Each URL has several parts. The general format of URL is as follows

Type: // address/ path

Here,

• Type specifies the type of server on which the web page is hosted
• Address specifies the address of server
• Path specifies the path of web of web page on the disk of sever.

Example

http:/ www.google.com/services/index.html

• http stands for hypertext transfer protocol. It is used to access websites on Internet.
• www stands for world wide web
• google indicates the name of the website
• com indicates the type of website
• /services indicate subdirectory services. Slash "/" indicates start of a subdirectory.
• Index.html indicates the name of the specific page in web site.

Web Server

What is web server?

Web server is a computer that is used to store information for the users on the Internet. A web server is much faster and powerful than ordinary computer. It may be located anywhere in the world. The servers are connected to Internet 24 hours a day. The web sites published on WWW are stored on web servers. The users read data and information from these web servers.

WWW

Define WWW?

WWW stands for World Wide Web. It is also called web it was launched in 1989 at the European Particle Physics Laboratory in Geneva. It provides the facility to publish information on the Internet. It is a collection of documents or web pages stored on computers permanently connected with Internet around the world.

A web page is a document that is written in HTML. These web pages are connected to one another using hyperlinks. The www uses hypertext transfer protocol (http) to link these web pages. Web pages are also known as hypertext documents.  A web page may contain simple text, images and hyperlinks. Anyone can view web pages through a web browser.

A collection of related web pages is called website. Each website has a unique address. Websites are stored on a host computer on the Internet. These computers are known as web server. The process of launching a web page is called publishing the page.

Addressing Scheme

Addressing Scheme:

Internet addresses are used to access different computers on the internet. Each computer on the internet has a unique address. This address is used to establish a connection with that computer. There are two types of addressing schemes on internet

1. IP Addressing: IP address is a unique number that refers to a computer connected to the internet. IP stands for Internet Protocol. This address is a 32 bit number. It consists of four numbers separated by period. Each number is between 0 to 255. These numbers are known as octets. like 192.168.1.1
2. DNS Addressing: IP address is difficult to remember for the users. All servers on the internet also have human readable name. It is known as domain name. A domain name consists of text instead of number. It is easier to remember a domain name than IP address. For example www.hotmail.com is a permanent and human readable name. It is easier to remember than IP address. It has two parts

• Hot name
• Domain

Internet Working

Working of Internet:

The internet is a collection of millions of computers. These computers are linked together on a computer network. The network is used by the computers to communicate with one another. A personal computer can be connected to internet by using phone line, DSL or cable modem.

A computer in a university or business is usually connected with local area network using network interface card (NIC).

Internet service provider are connected to larger ISPs. The largest ISPs maintain fiber optic backbones for an entire region.

Internet History

History of Internet:

The work on internet was started in 1960s during the cold war of Russia and America. America wanted to communicate with its Armed Forces. A network of four computers was developed in the beginning. The project was handed over to DARPA (Defense Advanced Research Project Agency). It started connection computers at different universities and defense companies.

Different universities and research organizations also started the development of their own networks to share information and data with other people.

Internet

Internet:

Internet is a huge collection of computers all over the world that are connected to one another. It is a global network of computers. These computers are connected through different telecommunications links like:

• Phone lines
• Fiber Optics lines
• Satellites and wireless connections

Internet is used to find information stored on the computers called hosts or severs. These computers use a common protocol called TCP/IP for communication.

High & Low Level Languages

Describe high-level and low-level languages

1.      Low Level Languages

            Low-level languages are near to computer hardware and far from human languages. The two low-level languages are machine language and assembly language.

i.            Machine Language

            A type of language in which instructions are written in binary form is called machine language. It is the only language that is directly understood by the computer. It is the fundamental language of the computer.

ii.            Assembly Language

            Assembly language is a low-level language. It is one step higher than machine language. In assembly language, symbols are used instead of binary code. These symbols are called mnemonics. For example Sub instruction is used to subtract two numbers. Assembly language is also called symbolic language.

2.      High Level Languages

            A type of language that is close to human languages is called high level language. High-level languages are easy to understand. Instructions of these languages are written in English-like words such as input and print etc.

Examples

        i. BASIC        ii. FORTRAN           iii. COBOL

iv. C / C++      v. Java                      vi. Visual Basic

Computer Language

Computer Language

A programming language is used to write computer programs. It is a means of communication between user and the computer. A large number of programming languages are available for writing programs. The programmer selects a programming language according to the nature of the program. There are two categories of computer programming languages. These are low-level languages and high-level languages.

Type of Programming Languages

There are two types of computer programming languages:

• Low-level languages     
• High-level languages

Function of OS

Discuss different functions of operating system.

Operating system performs the following function:

• Booting

Booting is a process of starting or restarting the computer. Operating system starts the computer to work. It checks the computer and makes it ready to work.

• Memory Management

It is also an important function of operating system. The memory cannot be managed without an operating system. Different programs and data execute in memory at one time. If there is no operating system, the programs may mix with each other. The system will not work properly.

• Loading and Execution

A program is loaded in the memory before it can be executed. Operating system provides the facility to load programs in memory easily and then execute it.

• Data Security

Data is an important part of computer system. The operating system protects the data stored on the computer from illegal user, modification or deletion.

• Disk Management

Operating system manages the disk space. It manages the stored files and folders in a proper way.

• Process Management

CPU can perform one task at one time. If there are many tasks, operating system decides which task should get the CPU.

• Device Controlling

Operating system controls all devices attached to computer. The hardware devices are controlled with the help of small software called device drivers.

• Printing Controlling

Operating System also controls printing function. If a user issues two print commands at a time, it does not mix data of these files and prints them separately.

• Providing Interface

User interface is used to interact with the computer. User Interface controls how you enter data and instructions and how information is displayed on the screen. Operating system provides two types of interfaces for the user:

Graphical User Interface: It consists of visual environment to communicate with the computer. It uses windows, icons, menus and other graphical objects to issues commands.

Command-line Interface: It provides an interface to communicate with the computer by typing commands.

Physical Layer

Physical Layer:

It is the bottom layer of OSI Model. It transmits stream of bits and defines how the data is transmitted over the network and what control signals are used. Its main function is to control how a stream of bits is sent and received over the physical medium. The following function performed by the physical layer.

1. Characteristics of Media: It layer define the characteristics and type of transmission medium.
2. Transmission Mode: The physical layer defines the direction of transmission between two devices simplex, half duplex or full duplex.
3. Data Rate: It define the number of bit that will be sent in each second.

Data Link Layer

Data Link Layer:

It responsible for the reliability of the physical link established at layer 1. The data link layer perform the following function:

1. Framing: The data link layer divides the stream of bits into manageable data units called frames.
2. Flow Control: The rate of sending data can be more than the rate of receiving data. Data link layer imposes flow control mechanism to prevent it.
3. Error Control: The data link layer detects and retransmits damaged lost frames. It also prevents the duplication of frames.
4. Access Control: If two or more devices are connected to the same link, data link layer determines which device has control over the link at a given time.

Network Layer

Network Layer:

It responsible for establishing, maintaining, and terminating network connections. it manages the delivery of data form source to destination.

Network layer determines logical path between sender and receiver. There may be many networks between two computers. This layer manages to send data from source to destination computer

Session Layer

Session Layer:

The session layer establishes, manages, and terminates user connections. A session is an exchange of message between computers. It synchronizes user task.

Synchronization involves the use of checkpoint in data stream. If a failure occurs, only the data from the last checkpoint is retransmitted. Suppose  we want to send 500 pages of data. Checkpoint can be used aster each 50 pages. if there is an error ate page 130, the pages from 101 will be retransmitted. Page from 1 to 100 will not be retransmitted.

Transport Layer

Transport Layer:

It layer controls the flow of data. It ensures that messages are delivered error free. It divides large messages into small packets for efficient transmission. These packets are reassembled, checked for errors and acknowledged at receiving side. If there are errors in transmission, the data is retransmitted.

Presentation Layer:

Presentation Layer:

It perform the following functions

1. Data Reformatting: When two computers exchange data, the data is changed to bit streams before it is transmitted. The computers may use different encoding techniques. The presentation layer at sending computer changes data according to the sender’s format. The presentation layer at receiving computer changes data according to the receiver’s format.
2. Encryption: The presentation layer encrypts data before transmission. It means that the sender transform the original information to another form and sends resulting message over the network. The receiver again transforms the message back to its original form. It is called decryption.
3. Compression: Data compression reduces the number of bits to be transmitted. The presentation layer compresses a large amount of data into small size.

Application Layer

Application Layer:

It is a top most layer of OSI Model. it provides services directly to user applications. It enable the user to access the network. It provides the user interfaces and support for services such as email, remote file access and transfer, shared database management and other types of distributed information services.

1. File Transfer: It allows a user to access, retrieve and manage files in a remote computer.
2. Mail Services: It provides the basis for email forwarding and storage facilities.
3. Directory Services: It provides distributes database sources and access for global information about various objects and services.

OSI Model

OSI Model

OSI stands for Open System Interconnection. An open system is a model that allows any two systems to communicate even if their architectures are different. OSI model was developed by International Standards Organization (ISO) in 1983. It provides logical framework for data communication processes to interact across networks. The standards were created for computer industry to allow different networks.

This model consists of seven layers. Each layer performs a specific functions in a network communication. The layer are divided into two groups:

Upper Layer: The upper layers focus on user applications and how files are represented on computers before transfer.

Lower Layer: The lower layers are concerned with how the communication across a network actually occurs.

Different Layers of OSI Model:

7. Application Layer

6. Presentation Layer

5. Session Layer

4. Transport Layer

3. Network Layer

2. Data Link Layer

1. Physical Layer

Types of partition

Types of partitions

Two types of partitions are as following:

• Primary partition

It is a type of partition that can be used as system partition. The system partition contains the hardware specific files required to load windows.

A primary partition can be created to occupy the entire hard disk or a portion of it.

Any hard disk can have a many partitions. All partition can be primary partitions. Each partition must be formatted after partitioning.

• Extended partition

It is a type of partition that can be further divided into sub partitions. The sub partitions are known as  logical partitions. it is done to use multiple operating systems. A hard disk can have only one extended partition It can also be formatted to create drives.

Partition

Define partition

Disk partition is a disk management technique. It is the logical division of the hard disk. A hard disk can contain one or more partitions. Partitioning is useful if the user wants to use multiple operating systems.

Computer Bus

Bus Interconnection

A computer system consists of different devices such as CPU, main memory and I/O devices. These devices are connected to an internal communication channel of the computer system to transfer data between these devices. The internal communication channel of the computer system is called bus interconnection.

Computer Bus

A bus consists of a set of parallel lines. It is used to transfer data between different components of the computer. Once line of bus can transfer one bit at a time.

The capacity if computer bus depends on the number of data lines in it. A bus with 16 lines can carry 16 bits or 2 bytes of data at a time. A bus with 32 lines can carry 32 bits or 4 bytes of data at a time. The amount of data that a bus can be carry at one time is called bus width.

Types of Buses

Different types of buses are as follows:

• System Buses

System bus is used to connect the main components of computer such as CPU and main memory .System buses are part of motherboard. Computers normally have system bus of 70 -100 lines

• Expansion Buses

Expansion bus is used to connect CPU with peripheral devices such as mouse, keyboard printer, modem and scanner etc.

Types of system buses

Discuss types of system buses.

Different types of system buses are as follows:

Data Bus

Data bus is the most common type of bus. It is used to transfer data between different components of computer. The number of lies in data bus affects the speed of data transfer between different components. The data bus consists of 8, 16, 32, or 64 lines. A 64- lines data bus can transfer 64 bits at one time.

The data bus lines are bi-directional. It means that:

CPU can read data from memory using these lines

CPU can write data to memory locations using these lines

Address Bus

Many components are connected to one another through buses. Each component is assigned a unique ID. This ID is called the address of that component. If a component wants to communicate with another component, it uses address bus to specify the address of that component. The address bus is a unidirectional bus. It can carry information only in one direction. It carries address of memory location from microprocessor to the main memory.

Control Bus

Control bus is used to transmit different commands or control signals from one component to another component. CPU wants to read data from main memory .It will use control bus to send the memory read command to the main memory of computer. The control bus is also used to transmit control signals like ACKS ( Acknowledgement signals)

Copyright

Software copyright       

          The permission given by a software developing company or person to use the software is called copyright. Any software is the properly of the person who develops it. It is his right to allow anybody or organization to use his software. This permission is given when a person or organization purchases this software.

          Good software takes a lot of time, cost and effort to build. It should not be used without the permission of the developer. Copyright laws ensure that no body should be allow to use any software without getting license from the developer.

          The software companies normally distribute software on CD ROM, which can easily be copied on more than computers. In the counties like Pakistan, there is no implementation of copyright laws, which makes it more difficult for software companies to develop to develop good software because they cannot get the reward of their work.

Crime of Computer

Computer Crime

          It is a type of crime that is committed by using computer technology. It requires special knowledge and expert use of computer technology. Computer have been used in different types of crimes such as theft, fraud, kidnapping and murder etc.

          Computer system themselves can be the targets of attack. A hacker may break into a computer system to commit a crime. Some serious computer crimes are committed in the banking and financial organization. Banks store the records in computers and a hacker may access the computer and manipulate the records for false purpose. The money can be illegally transferred to different accounts etc.

Types of Virus

Types of virus

There are following:

• Boot Sector Virus

A disk divide into tracks and sectors. The disk that contains operating system has a special program in its first sector. The sector is known as boot sector. The program in boot sector is automatically loaded in memory when computer starts. The program then loads operating system in the memory. The boot sector virus modifies the program in the boot sector.

• Chernobal  Virus

The famous chernobal virus deletes all Microsoft Office files. It also deletes the partition information from the disk that causes a major loss of data.

• Logic Bomb

Logic bomb is also called time bomb. It differs from other viruses. It is activated at a certain date and time. Michelangelo is an important logic bomb. It destroy data on the hard disk on August 20.

• Trojan Horse.

Trojan Horse hides itself as useful program. it contains hidden instruction to erase data or cause other damage. It execute illegal, destructive instructions in the middle of a program such as computer game. FormatC is an example of a Trojan Horse.

• Redlof

It is a polymorphic virus. it is written in Visual Basic Script. it relies on the Microsoft Active X component to execute itself. It locates Folders.htt and infects that file.