hi rihaana A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user. The term "virus" is also commonly used, albeit erroneously, to refer to many different types of malware and adware programs. The original virus may modify the copies, or the copies may modify themselves, as occurs in a metamorphic virus. A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or the Internet, or by carrying it on a removable medium such as a floppy disk, CD, or USB drive. Meanwhile viruses can spread to other computers by infecting files on a network file system or a file system that is accessed by another computer. Viruses are sometimes confused with computer worms and Trojan horses. A worm can spread itself to other computers without needing to be transferred as part of a host, and a Trojan horse is a file that appears harmless. Worms and Trojans may cause harm to either a computer system's hosted data, functional performance, or networking throughput, when executed. In general, a worm does not actually harm either the system's hardware or software, while at least in theory, a Trojan's payload may be capable of almost any type of harm if executed. Some can't be seen when the program is not running, but as soon as the infected code is run, the virus kicks in. That is why it is so hard for people to find viruses themselves and why they have to use spyware programs and registry processors.

Most personal computers are now connected to the Internet and to local area networks, facilitating the spread of malicious code. Today's viruses may also take advantage of network services such as the World Wide Web, e-mail, Instant Messaging and file sharing systems to spread, blurring the line between viruses and worms. Furthermore, some sources use an alternative terminology in which a virus is any form of self-replicating malware.

Some viruses are programmed to damage the computer by damaging programs, deleting files, or reformatting the hard disk. Others are not designed to do any damage, but simply replicate themselves and perhaps make their presence known by presenting text, video, or audio messages. Even these benign viruses can create problems for the computer user. They typically take up computer memory used by legitimate programs. As a result, they often cause erratic behavior and can result in system crashes. In addition, many viruses are bug-ridden, and these bugs may lead to system crashes and data loss. Many CiD programs are programs that have been downloaded by the user and pop up every so often. This results in slowing down of the computer, but it is also very difficult to find and stop the problem
for more inf check source http://en.wikipedia.org/wiki/Comput er_virus

Answered by laks , an ibibo Master, at 2:46 PM on May 16, 2008

Computer viruses are programs written by "mean" people. These virus programs are placed into a commonly used program so that program will run the attached virus program as it boots, therefore, it is said that the virus "infects" the executable file or program. Executable files include Macintosh "system files" and application programs Viruses work the same ways in Windows or DOS machines by infecting zip or exe files.

A virus is inactive until you execute an infected program or application OR start your computer from a disk that has infected system files. Once a virus is active, it loads into your computer's memory and may save itself to your hard drive or copies itself to applications or system files on disks you use.

Some viruses are programmed specifically to damage the data on your computer by corrupting programs, deleting files, or even erasing your entire hard drive. Many viruses do nothing more than display a message or make sounds / verbal comments at a certain time or a programming event after replicating themselves to be picked up by other users one way or another. Other viruses make your computer's system behave erratically or crash frequently. Sadly many people who have problems or frequent crashes using their computers do not realize that they have a virus and live with the inconveniences.

How to Prevent a Virus Invasion!

1. Load only software from original disks or CD's. Pirated or copied software is always a risk for a virus.
2. Execute only programs of which you are familiar as to their origin. Programs sent by email should always be suspicious.
3. Computer uploads and "system configuration" changes should always be performed by the person who is responsible for the computer. Password protection should be employed.
4. Check all shareware and free programs downloaded from on-line services with a virus checking program.
5. Purchase a virus program that runs as you boot or work your computer. Up-date it frequently.

Answered by Nagendra , an ibibo Master, at 6:23 AM on May 03, 2008

computer virus is nothing but script written in various languages like javascript, c assembly language, & so on, which affect your computer like deletion of files, then add unwanted files, then steal data etc.

Answered by Dinesh , an ibibo Citizen, at 7:54 PM on April 25, 2008

A computer program file capable of attaching to disks or other files and replicating itself repeatedly, typically without user knowledge or permission. Some viruses attach to files so when the infected file executes, the virus also executes. Other viruses sit in a computer’s memory and infect files as the computer opens, modifies or creates the files. Some viruses display symptoms, and some viruses damage files and computer systems, but neither symptoms nor damage is essential in the definition of a virus; a non-damaging virus is still a virus.

Answered by Deepak , an ibibo Master, at 10:09 PM on April 23, 2008

A computer program that can harm a computer by displaying messages, deleting files, or even destroying the computer's operating system.
A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user. The term "virus" is also commonly used, albeit erroneously, to refer to many different types of malware and adware programs. The original virus may modify the copies, or the copies may modify themselves, as occurs in a metamorphic virus. A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or the Internet, or by carrying it on a removable medium such as a floppy disk, CD, or USB drive. Meanwhile viruses can spread to other computers by infecting files on a network file system or a file system that is accessed by another computer. Viruses are sometimes confused with computer worms and Trojan horses. A worm can spread itself to other computers without needing to be transferred as part of a host, and a Trojan horse is a file that appears harmless. Both worms and Trojans will cause harm to computers when executed. Some can't be seen when the program is not running but as soon as the program is started, the virus kicks in, and that is why it is so hard for people to find viruses themselves and and why they have to use spyware programs and registry processors.
Most personal computers are now connected to the Internet and to local area networks, facilitating the spread of malicious code. Today's viruses may also take advantage of network services such as the World Wide Web, e-mail, Instant Messaging and file sharing systems to spread, blurring the line between viruses and worms. Furthermore, some sources use an alternative terminology in which a virus is any form of self-replicating malware.
Some viruses are programmed to damage the computer by damaging programs, deleting files, or reformatting the hard disk. Others are not designed to do any damage, but simply replicate themselves and perhaps make their presence known by presenting text, video, or audio messages. Even these benign viruses can create problems for the computer user. They typically take up computer memory used by legitimate programs. As a result, they often cause erratic behavior and can result in system crashes. In addition, many viruses are bug-ridden, and these bugs may lead to system crashes and data loss. Many CiD programs are programs that have been downloaded by the user and popup every so often. This results in slowing down of the computer, but it is also very difficult to find and stop the problem.

Answered by jaivir , an ibibo Master, at 7:58 PM on April 23, 2008

its a program used to destroy softwares

Answered by DRIVE100 SS , an ibibo Citizen, at 6:26 PM on April 23, 2008

A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user. The term "virus" is also commonly used, albeit erroneously, to refer to many different types of malware and adware programs. The original virus may modify the copies, or the copies may modify themselves, as occurs in a metamorphic virus. A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or the Internet, or by carrying it on a removable medium such as a floppy disk, CD, or USB drive. Meanwhile viruses can spread to other computers by infecting files on a network file system or a file system that is accessed by another computer. Viruses are sometimes confused with computer worms and Trojan horses. A worm can spread itself to other computers without needing to be transferred as part of a host, and a Trojan horse is a file that appears harmless. Both worms and Trojans will cause harm to computers when executed. Some can't be seen when the program is not running but as soon as the program is started, the virus kicks in, and that is why it is so hard for people to find viruses themselves and and why they have to use spyware programs and registry processors.

Answered by ayisha , an ibibo Master, at 5:37 PM on April 23, 2008

A dangerous computer program with the characteristic feature of being able to generate copies of itself, and thereby spread throughout the computer system. Additionally, most computer viruses have a destructive payload that is activated under certain conditions.

Answered by Archit , an ibibo Advisor, at 4:10 PM on April 23, 2008

A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves. All computer viruses are manmade. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.

Answered by RushON , an ibibo Citizen, at 3:33 PM on April 23, 2008