A computer virus is a program, or piece of code, that is written to interfere with, and harm, your machine. A virus can replicate itself, spread to other computers, and attack other programmes on your computer. (By attack, we mean change or delete files.) Computer experts distinguish between a virus, a worm, and a Trojan. Here’s the differences:
Virus – Can replicate and spread to other computers. Also attacks other programes
Worm – A special type of virus that can replicate and spread, but generally doesn’t attack other programesTrojan – Doesn’t replicate, but can spread. Doesn’t attack other programmes. Usually just a way of recording and reporting what you do on your PCViruses are split into different categories, depending on what they do. Here are a few categories of viruses:
Boot Sector Virus
The Boot Sector of a PC is a part of your computer that gets accessed first when you turn it on. It tells Windows what to do and what to load. It’s like a “Things To Do” list. The Boot Sector is also known as the Master Boot Record. A boot sector virus is designed to attack this, causing your PC to refuse to start at all !
A file virus, as its name suggests, attacks files on your computer. Also attacks entire programes, though.
These types of virus are written specifically to infect Microsoft Office documents (Word, Excel PowerPoint, etc.) A Word document can contain a Macro Virus. You usually need to open a document in an Microsoft Office application before the virus can do any harm.
A multipartite virus is designed to infect both the boot sector and files on your computer
This type of virus alter their own code when they infect another computer. They do this to try and avoid detection by anti-virus programes.