What is computer virus?

 Computer Virus And Antivirus

One thing that all computer users may have in common is fear of contracting a virus on their systems. Computer and its data is critical for us. An accidental event with data causes the loss of many hours hard work and analysis.

COMPUTER VIRUS
A computer virus is a program or a set of programs that disrupts the normal operation of a computer. Virus infects or destroys data. It enters in the computer without the permission or knowledge of the user.
Virus is a Latin word which means poison. The Full form of VIRUS is Vital Information Resources Under Seize. The essential resources of the computer like memory, processing speed, data and programs etc. cannot have normal operations and can be harmed, when virus is spread.
Virus programs are self-replicating and are continuously expanding their reach by infecting more and more computer files, resulting in loss of speed and destruction of data. Computer programs are written to instruct the computer what the user wants it to do. But Virus programs make the computer do those things which you never want. Normally, it enters through an infected pen drive or Internet/E-mail. To avoid detection, they are secretly hidden. Virus programs can remain undetected and quietly inactive for a long time waiting for a particular signal or an event to trigger them. E.g., Some virus programs monitor the clock in the host computer and trigger on a certain day, like Friday the 13th. Some viruses are harmless. They display simple message. But most of the viruses are harmful. Viruses are written by destructive sources who just want to amuse them selves. Their authors given them fancy name like AIDS, Saturday 14, Dark Avenger and Friday the 13th.
A computer virus is a program. It should not be confused with the medical term virus which is an organism. However, both of them have the same features as far as their destructive activities are concerned. Major difference between the two is that a biological virus causes physical harm to our body and attack certain cells, whereas, computer virus causes harm to the data and programs stored in a computer by overwriting them with garbage or erasing them.

Damages Caused by Virus
Computer virus cannot damage computer hardware. A virus can do the following damages:
1. A computer virus can damage data or software on the computer.
2. It can delete some or all files on the computer system.
3. It can destroy all the data by formatting hard drive.
4. It may display false message very few times.

Symptoms of a Computer Virus
The symptoms that occur when a computer is affected by a computer virus are as
follows:
1. The computer might run slower.
2. It might corrupt your system files.
3. It might make some programs faulty or corrupt.
4. Frequent hanging of the systems.
5. It makes endless copies of infected files on the system.
6. Strange sounds or beeping noises come from the computer or keyboard.
7. Unusual error messages are displayed on the computer monitor.
8. The hard drive often runs out of free space.
9. Application programs on the computer do not work correctly or smoothly.
10. It might steal important information from your computer and send them to the other people through the Internet.

How Does the Computer Gets Infected?
 The computer gets infected with a virus in many ways. Few of them are listed below:
1. CD/Pen Drives or Other Portable Devices: CD/Pen Drives are the main cause of spreading virus. These are used to transfer data from one computer to other. A virus can also be copied from one computer to other when the user copies infected files using flash drives and disks.
2. From E-mail : Virus may enter into your computer system through email attachments. The attachments that you receive from unknown users may be virus.
3. From the Internet : Virus may enter through various malicious websites. For example, when you download some files from the internet, they may be infected files which put your computer at risk.
4. From a Computer Networks : A computer network is a large collection of several computer systems connected by a large/main computer called a server. These computers constantly share information. Any infected file may spread the virus.
5. Pirated Software: An illegal copy of software is called pirated software. Virus can
spread if user installs pirated software that contains a virus. A variety of pirated
software is available in CDs and from the Internet.

PROTECTING THE COMPUTER FROM VIRUSES
Protection of computer from viruses is not a difficult task. A computer system can be
protected from virus by following these precautions:
1. USB drives should be scanned for viruses and should not be used on infected computer.
2. Unauthorized or pirated software should not be installed on the computer.
3. Scan the hard disk twice a month.
4. Take the back up of important files everyday.
5. Use internet and e-mail attachments very carefully.
6. Install an antivirus program on the computer and scan the system with antivirus software regularly.
7. Regularly update antivirus software.
8. Keep system's Firewall ON.

ANTIVIRUS SOFTWARE
Antivirus software is a utility software program that are installed on your computer to protect it from viruses. Antivirus perform the following tasks in a computer: Scan the computer files to look for known viruses matching definitions from virus dictionary.
Identify suspicious behaviour from any computer program which might indicated infection.
Simply installing an Antivirus software in our computer does not guarantee 100% protection, as the installed Antivirus program would not be able to detect new virus programs. We should keep on updating our computer with the latest versions of Antivirus programs. Most of the Antivirus software companies provide the facility to download the latest updates from their websites. Some of the popular Antivirus programs are: