What is a computer viruses?

Answer 1

Firstly, it should be 'What are Computer Viruses?', or 'What is a computer virus?'. But to answer the question, a virus is a a harmful or malicious script or code which may harm your computer. These should not be confused with Trojans or Worms.

TrojansTrojans horses are just like in the story of troy: They are something bad wrapped up in something good. You may be downloading a video from the internet and get the video, but with it will come a device that will attempt to hack your computer or get you to buy some piece of software for a very high price. A Trojan horse is a file that appears harmless until executed.

A good example is WinAntiVirus, a Trojan that comes bundled with a download that you, yourself wanted to download. It convinces you that there are hundreds of viruses on your computer, that this "new and efficient" program can detect. It will try and make you buy the full WinAntiVirus for hundreds of dollars or pounds, and when you buy it the whole thing clears off of your system, leaving you confused with empty pockets. Something even more shocking is that the person who owns WinAntiVirus makes nearly 6 million dollars (3 and a half million pounds) every year. Bear in mind that YOU MUST DOWNLOAD THE TROJAN FOR IT TO GET ONTO YOUR SYSTEM. Most good antivirus systems will get rid of these trojans.

VirusesA computer virus is a script that can copy itself and infect a computer without permission or knowledge of the user. However, the term "virus" is commonly used, albeit erroneously, to refer to many different types of malware 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. Additionally, viruses can spread to other computers by infecting files on a network file system or a file system that is accessed by another computer.

In easier language, viruses can copy themselves, and those copies can copy themselves, but all copies can do the same thing-usually destroy files (which could be critical files) or hack the system (attempting to obtain personal details).

WormsFinally, a worm is the most independent. A worm can spread itself to other computers without the user actually doing anything. A good example is an email worm. An email worm comes in an email, and as soon as the user opens it the worm duplicates the email, sending it to all contacts on the users list. When those users open it the same thing happens, so the link can go on forever. Sometimes they are harmless, but it is more common that they delete files-causing a nuisance to the user. In some cases the worm may permanently shut down your computer. Worms usually come in the form of Spam.

Answer 2

self-replicating computer program written to alter the way a computer operates, without the permission or knowledge of the user. mike was here