Virus

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A virus is a computer code or program, which is capable of affecting your computer data badly by corrupting or destroying them.

Computer virus has the tendency to make its duplicate copies at a swift pace, and also spread it across every folder and damage the data of your computer system.

A computer virus is actually a malicious software program or "malware" that, when infecting your system, replicates itself by modifying other computer programs and inserting its own code.

Infected computer programs may include data files, or even the "boot" sector of the hard drive.

Types of Virus

Following are the major types of computer virus −

Worms

This is a computer program that replicates itself at a swift pace. Unlike a computer virus, it is self-contained and hence does not need to be part of another program to propagate itself.

Trojan Horse

A Trojan Horse is also a sort of destructive program that remains disguised in a normal software program. It is not exactly a virus, as it cannot replicate itself. However, there is possibility that virus program may remain concealed in the Trojan Horse.

Bombs

It is similar to Trojan Horse, but Logic bombs have some specialty; these include a timing device and hence it will go off only at a particular date and time.

How Does Virus Affect?

Let us discuss in what ways a virus can affect your computer system. The ways are mentioned below −

• By downloading files from the Internet.
• During the removable of media or drives.
• Through pen drive.
• Through e-mail attachments.
• Through unpatched software & services.
• Through unprotected or poor administrator passwords.

Impact of Virus

Let us now see the impact of virus on your computer system −

• Disrupts the normal functionality of respective computer system.
• Disrupts system network use.
• Modifies configuration setting of the system.
• Destructs data.
• Disrupts computer network resources.
• Destructs of confidential data.

Virus Detection

The most fundamental method of detection of virus is to check the functionality of your computer system; a virus affected computer does not take command properly.

However, if there is antivirus software in your computer system, then it can easily check programs and files on a system for virus signatures.

Virus Preventive Measures

Let us now see the different virus preventive measures. A computer system can be protected from virus through the following −

• Installation of an effective antivirus software.
• Patching up the operating system.
• Patching up the client software.
• Putting highly secured Passwords.
• Use of Firewalls.

Most Effective Antivirus

Following are the most popular and effective antivirus from which you can choose one for your personal computer −

• McAfee Antivirus Plus
• Symantec Norton Antivirus
• Avast Pro Antivirus
• Bitdefender Antivirus Plus
• Kaspersky Anti-Virus
• Avira Antivirus
• Webroot Secure Anywhere Antivirus
• Emsisoft Anti-Malware
• Quick Heal Antivirus
• ESET NOD32 Antivirus

Threat

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Threat in a computer system is a possible danger that might put your data security on stake. The damage is at times irreparable.

Definition

As defined by the National Information Assurance Glossary −

• “Any circumstance or event with the potential to adversely impact an IS through unauthorized access, destruction, disclosure, modification of data, and/or denial of service.”

• A computer threat can be "intentional" such as hacking or "accidental" such as malfunctioning of or physical damage.

Types of Threat

Following are the most common types of computer threats −

• Physical damage − It includes fire, water, pollution, etc.

• Natural events − It includes climatic, earthquake, volcanic activity, etc.

• Loss of services − It includes electrical power, air conditioning, telecommunication, etc.

• Technical failures − It includes problems in equipment, software, capacity saturation, etc.

• Deliberate type − It includes spying, illegal processing of data, etc.

Some other threats include error in use, abuse of rights, denial of actions, eavesdropping, theft of media, retrieval of discarded materials, etc.

Sources of Threat

The possible sources of a computer threat may be −

• Internal − It includes employees, partners, contractors (and vendors).

• External − It includes cyber-criminals (professional hackers), spies, non-professional hackers, activists, malware (virus/worm/etc.), etc.

Common Terms

Following are the common terms frequently used to define computer threat −

Virus Threats

A computer virus is a program designed to disrupt the normal functioning of the computer without the permission of the user.

Spyware Threats

Spyware is a computer program that monitors user’s online activities or installs programs without user’s consent for profit or theft of personal information.

Hackers

Hackers are programmers who put others on threats for their personal gain by breaking into computer systems with the purpose to steal, change or destroy information.

Phishing Threats

It is an illegal activity through which phishers attempt to steal sensitive financial or personal data by means of fraudulent email or instant messages.

How to Secure Your Computer System from Threats?

Following are the significant tips through which you can protect your system from different types of threat −

• Install, use, and keep updated Anti-Virus in your system.
• Install, use, and keep updated a Firewall Program.
• Always take backups of your important Files and Folders.
• Use Strong and Typical Passwords.
• Take precaution especially when Downloading and Installing Programs.
• Install, use, and keep updated a File Encryption Program.
• Take precaution especially when Reading Email with Attachments.
• Keep your Children aware of Internet threats and safe browsing.

Security

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Advancement of computer technology has radically changed the world; resultantly, most of the works whether it is matter of nation’s security system or buying a shoe online everything depends on computer.

Such increased dependency also raises the issue of security, as most of the data is now stored in the computer system.

Your computer systems store various sorts of data and hence if it is not secured, then you might be in for a big trouble.

Why Do We Computer Security?

Let us now see why do we need Computer security. It is required for the following major reasons −

• To prevent damage of the hardware.

• To prevent theft or damage of the installed software.

• To prevent theft or damage of stored data and information.

• To prevent the disruption of service.

• Likewise, security system keeps the computer system safe by protecting the installed software and the stored data (information).

Protection of Data and Information

Following are the important steps to protect data −

• Make backup of all your important files.
• Keep your system virus by using anti-virus software.
• Keep updating your computer system.
• Run disk defragmenter and disk cleanup on certain interval of time.
• Use a firewall.
• Use anti-spyware software.

Further, if you use internet, then you need to take greater precaution. Consider the following points to understand the precautions that need to be taken −

• Do not click on any link that you don’t know (as it may be dangerous for your computer - virus attack).

• Do not open unauthorized an unlawful website (it may damage your computer system).

• Do not download unsolicited data from unknown website.

What is Defragmentation?

Frequent saving and deleting of file (data) from the hard disk creates problems in performance and also reduce the space; therefore, defragmentation again clean-up the drive and restore the system to run smoothly.

Following are the simple steps of defragmentation −

Disk Cleanup

While browsing websites (on internet), many of the files get stored in the hard disk automatically (actually these stored files later help to reopen the website faster); besides some other cookies also get stored in the hard disk. All these stored files create problem along with eating space.

So, disk cleanup process cleans all these files and releases the space occupied by these unwanted files.

Following are the simple steps of disk cleanup −

Multimedia

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In this chapter, we will discuss how the Computer Multimedia works. If a system presents, some information through more than two media, it is known as multimedia. For example, TV presents audio and video; book presents text, image, and graphs, computer, etc.

The information presented through multimedia has better quality and capability, as it can be understood easily.

The advanced computer system is a great example of modern multimedia.

Literal Meaning of Multimedia

In this section, we will understand the literal meaning of multimedia.

• Multi − it means more than one

• Medium − it is singular and it means intermediary or mean

• Media − it is plural and it means conveying the information

Likewise, Multimedia is the field of Computer Science that integrates different forms of information and represents in the form of audio, video, and animation along with the traditional media, i.e., text, graphics/drawings, images, etc.

Multimedia Computer System

Multimedia computer system has high capacity to integrate different media including text, image, graphics, audio, and video.

The multimedia computer system stores, represents, processes, manipulates, and makes available to users.

Significant Features of Multimedia Computer System

Following are the major features multimedia computer system −

• Its Central Processing Unit (CPU) is very fast, as it needs to process large amount of data.

• It has huge storage capacity.

• It has huge memory power that helps in running heavy data programs.

• It has high capacity graphic card that helps in displaying graphics, animation, video, etc.

• The sound system makes it easy to listen to audio.

• With all these features (discussed above), a computer system is known as high end multimedia computer system.

• However, all the features listed above are not essentially required for every multimedia computer system, but rather the features of a multimedia computer system are configured as per the need of respective user.

Multimedia Components

Following are the major components of a multimedia computer system −

Text

It contains alphanumeric and some other special characters. Keyboard is usually used for input of text; however, there are some internal (inbuilt) features to include such text.

Graphics

It is technology to generate, represent, process, manipulate, and display pictures. It is one of the most important components of multimedia application. The development of graphics is supported by a different software.

Animation

Computer animation is a modern technology, which helps in creating, developing, sequencing, and displaying a set of images (technically known as ‘frames’). Animation gives visual effects or motion very similar to that of a video file (see image given below).

Audio

This technology records, synthesizes, and plays audio (sound). There are many learning courses and different instructions that can be delivered through this medium appropriately.

Video

This technology records, synthesizes, and displays images (known as frames) in such sequences (at a fixed speed) that makes the creation appear as moving; this is how we see a completely developed video. In order to watch a video without any interruption, video device must display 25 to 30 frames/second.

Multimedia Application

Let us now see the different fields where multimedia is applied. The fields are described in brief below −

Presentation

With the help of multimedia, presentation can be made effective.

E-books

Today, books are digitized and easily available on the Internet.

Digital Library

The need to be physically present at a library is no more necessary. Libraries can be accessed from the Internet also. Digitization has helped libraries to come to this level of development.

E-learning

Today, most of the institutions (public as well as private both) are using such technology to education people.

Movie making

Most of the special effects that we see in any movie, is only because of multimedia technology.

Video games

Video games are one of the most interesting creations of multimedia technology. Video games fascinate not only the children but adults too.

Animated films

Along with video games, animated film is another great source of entertainment for children.

Multimedia conferencing

People can arrange personal as well as business meetings online with the help of multimedia conferencing technology.

E-shopping

Multimedia technology has created a virtual arena for the e-commerce.

Windows Desktop Elements

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Once you are logged in a window computer system, you will get dozens of applications, so you can choose an option of your requirement.

Many of the options have shortcut icon readily available on your computer screen; however, in some computers, you may not find any such option on the screen; in such a case, you can take the help of menu button (as shown in the image given below) −

As you can see in the above image, in the left bottom, there is a window symbol (i.e., menu button); once you click on it, the given menu option will appear and from here you can choose your option.

Start Menu Options

The following table lists down the options that appear after clicking on the Start menu −

Sr.No.	Option & Description
1	All programs It displays all those programs, which are installed in your system.
2	Document It displays a list of folders used by the user.
3	Recent file It displays the recently used file.
4	My picture It displays a list of pictures.
5	My music It displays a list of music/song, etc.
6	My computer It displays the drives of computer where user keeps his/her work, file, folder, song, video, picture, e-book, etc.
7	Control panel It displays all the installed computer programs (software).
8	Printer It displays the installed printers (if printer is installed in the system, user can take print easily).
9	Help (support) It helps users to know how to do a particular task.
10	Search It helps a user to find a file in computer.
11	Run It helps to start an application program or execute a DOS command.
12	Setting It has different options that help to manage different settings of the computer, software as well as hardware.
13	Log Off It helps a user to log off the currently logged in user of the system.
14	Sleep It makes the system non-functional; however, puts the ongoing work and settings in memory and also keeps drawing small amount of power.
15	Hibernation Hibernation puts the open documents and programs on hard disk and then turns off your computer; in comparison to ‘sleep’, it uses very low power.
16	Restart Its function is to shut down and again start (log on) computer; it is done normally to refresh computer especially when computer is hanged.
17	Shut down It simply shuts down the system.

Note − Depending on the version of your window, the menu option may vary in terms of appearance and number of menu options; however, there would not be any change in basics.

Recycle Bin

Recycle Bin is a trash location where deleted files remain stored. Once you delete any sort of file, it gets stored (automatically) into recycle bin; therefore, if you mistakenly deleted some important file, don’t panic, go to recycle bin and restore it. However, if you deleted file from recycle bin as well, then it is very difficult to restore that permanently deleted file.

Internet Option

The option (i.e., short-cut key) of the Internet browser may be available on the main screen or at the bottom menu bar (as shown in the image given below). However, if do not find it at both these places, go to the menu, as all programs are listed there.

Mobile

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Mobile computers are the systems, which are physically not remain connected to specific place rather these are mobile in nature, as one can carry anywhere anytime.

The mobile computer technology carries battery back; therefore, it does not require consistent electric power.

Mobile computers can be connected with Internet through wire or the connection can be wireless as well through Wi-Fi or Bluetooth technology. Likewise, it is portable, self-powered (because of inbuilt battery), and infused with wireless technology computing device.

Types of Mobile Computing Device

Following are the popular mobile computing devices −

Laptop

A laptop is a portable version of desktop computer. It is equally competent to do any computing work.

Notebook

It is a light weight portable personal computer.

Tablet

It is comparatively handier slate-shaped mobile computer.

Smart Phone

A smart phone is a fully equipped cell phone with most of the computing features.

Personal Digital Assistant (PDA)

It is a computer device more popular as pocket computer. It is largely used in calculation, accessing the Internet, sending and receiving E-mails, scanning bar codes, use as a radio or stereo, playing computer games, video recording, typewriting and word processing, use as an address book, making and writing on spreadsheets, Global Positioning System (GPS), as a clock and calendar, etc.

Portable Data Terminal (PDT)

It is a computer device, which is largely used to enter or retrieve data through wireless transmission (i.e., WLAN or WWAN).

Mobile Data Terminal(MDT)

It is a computer device, which is used in police cars, taxi-cabs, military logistics, service trucks, commercial trucking fleets, courier vehicles, fishing fleets, etc.

Ultra-mobile Personal Computer (UMPC)

It is small form of tablet PC.

Extranet

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An extranet is a sort of personalized service, which is controlled and regulated by private network.

This personalized and controlled technology provides access only to partners, vendors, and suppliers; sometimes, not essentially, but also to some specific customers.

An extranet is a private network organization, which is actually the part of respective company’s intranet and its services are extended to users outside the company. Sometimes, it is also considered as a specialized technique to practice business with other companies and selling products to the customers.

In order to do business with other business partners, extranet technology facilitates the intranet from one location to other and also provides security to data flow.

An extranet service requires firewall server management in order to provide security and privacy.

Features of Extranet Services

Following are the significant features of extranet services −

• Extranet is an extended Internet service to the private business network.

• The services extend outside the corporate firewall.

• Sometimes, it can be referred to an Intranet, as it can be (partially) accessible to some outsiders (with permission).

• The technique of extranet links two (or more) business organizations who share common business goals.

Application of Extranet

Extranet can be applied for the following services −

• It facilitates collaborative business between two (or more) companies

• By using this technology, a joint training program (with other company) is conducted

• By using electronic data interchange, large volumes of data are shared swiftly

• It is used to share product catalogs especially with wholesalers

• Extranet service is also used in providing customer support

• It is used to share business news with partner companies

Advantages of Extranet

The advantages of Extranet services are as follows −

• It makes business (services) swift and faster.
• It helps greatly in improving the business communication.
• It helps in reducing the cost (especially in terms of stationery stuff).
• It helps in improving the efficiency and confidence of the employees.
• It reduces some big physical barriers (especially the geographical distance).

Major Fields Using Extranet

Following are some of the major fields that are using Extranet service on a large scale −

• Corporate houses
• Government offices
• Education centers

Intranet is more localized, as only internal employees have the accessibility. In contrast, Extranet covers a wider area, as outsiders (such as partner, vendor, or even customer) have the authorized accessibility.