what are computer viruses?

Question

how there reappear after we delete them?

Answer 1

http://askcomputerexpert.ws43.com/security/

Answer 2

A computer virus is a self-replicating computer program written to alter the way a computer operates, without the permission or knowledge of the user. Though the term is commonly used to refer to a range of malware, a true virus must replicate itself, and must execute itself. The latter criteria is often met by a virus which replaces existing executable files with a virus-infected copy. While viruses can be intentionally destructive—destroying data, for example—some viruses are benign or merely annoying.

Answer 3

A computer virus is a self-replicating computer program written to alter the way a computer operates, without the permission or knowledge of the user. Though the term is commonly used to refer to a range of malware, a true virus must replicate itself, and must execute itself. The latter criteria is often met by a virus which replaces existing executable files with a virus-infected copy. While viruses can be intentionally destructive—destroying data, for example—some viruses are benign or merely annoying.

Classification of virusses
Viruses can be subdivided into a number of types, the main ones being:

Boot sector viruses
Companion viruses
Email viruses
Logic bombs and time bombs
Macro viruses
Cross-site scripting virus
Two other types of malware are often classified as viruses, even though they may not meet the standard criteria:

Trojan horses
Worms

*Why people create computer viruses
Unlike biological viruses, computer viruses do not simply evolve by themselves. Computer viruses do not come into existence spontaneously, nor are they likely to be created by bugs in regular programs. They are deliberately created by programmers, or by people who use virus creation software. Computer viruses can only do what the programmers have programmed them to do.

Virus writers can have various reasons for creating and spreading malware. Viruses have been written as research projects, pranks, vandalism, to attack the products of specific companies, to distribute political messages, and financial gain from identity theft, spyware, and cryptoviral extortion. Some virus writers consider their creations to be works of art, and see virus writing as a creative hobby. Additionally, many virus writers oppose deliberately destructive payload routines. Some viruses were intended as "good viruses". They spread improvements to the programs they infect, or delete other viruses. These viruses are, however, quite rare, still consume system resources, may accidentally damage systems they infect, and, on occasion, have become infected and acted as vectors for malicious viruses. A poorly written "good virus" can also inadvertently become a virus in and of itself (for example, such a 'good virus' may misidentify its target file and delete an innocent system file by mistake). Moreover, they normally operate without asking for the permission of the computer owner. Since self-replicating code causes many complications, it is questionable if a well-intentioned virus can ever solve a problem in a way that is superior to a regular program that does not replicate itself.


Regards,
~hero~
www.akbarthegreat.com
Computer Engineer, Dubai, U.A.E

Answer 4

In computer security technology, a virus is a self-replicating program that spreads by inserting copies of itself into other executable code or documents (for a complete definition: see below). Thus, a computer virus behaves in a way similar to a biological virus, which spreads by inserting itself into living cells. Extending the analogy, the insertion of the virus into a program is termed infection, and the infected file (or executable code that is not part of a file) is called a host. ...

Answer 5

computer viruses are undesired files that hamper the health of your computer.Eg:-Friday the 13th:it is a virus that attacks the computer when the day and date is 13th of friday.
computer viruses can be deleted by using an antivirus program.
however each antivirus prg has its own problems.
using a combination of prgs. can be effective

Answer 6

a computer virus is a program that is made by sum1 to disrupt the normal functiong of other people's computers. it is a program generally written to perform undesirable tasks. internet happens2 b one of the major sourcrs of virusus. a virus may enter ur computer system as result of downloading an infected file.an evev more common way of virus entering ur system is in the form of an e-mail attachtment.

Answer 7

Viruses are programs which can create a copy of themselves and destroy your system's resources. They usually corrupt your Operating System. The best way to stay clear of them is to use a good anti-virus.

Answer 8

You have to instal a virus remover.
Try MaCAfee anti virus by Norton Associates.It is called:
Virus Enterprice 7.1

Answer 9

just data that forces itself in a program and renders it unreadable. its that simple
imagine

the computer wanted to read the word you
a virus in form 2#441!% combines itself with the word you and it is now y2#o441!u% from here the computer fails to read further.

hope its abit clear now

Answer 10

well computer viruses are software where bad things stop rubish getting in