What are computer viruses? Many computer users would find it hard to answer that question. In fact the definition of a virus has nothing to do with what terrible damage it may inflict on your computer. It is just a question of how it spreads. A virus is a program (usually a file ending in .exe) that has the ability to clone itself and transmit its clones to other computers. This system of ‘infection’, resembling the spread of viral diseases, is why it is called a virus.
Of course, unlike viral diseases, computer viruses are not carried by insects or spread by coughs and sneezes. Instead, their carriers are digital. Your computer may be infected with a virus by a data disk or CD that you insert, a file that you download from the internet, or an email. It is even possible to download a virus by simply visiting a web page and then clicking away.
What a virus does when it reaches your computer depends on what it is programmed to do. If it is an email-borne virus then the first thing it will do will be to try to spread itself on to your contacts, usually by sending out an email to everyone in your address book. Then it will go ahead and fulfill its primary purpose. This can be almost anything from displaying a message on your screen through corrupting your files and even wiping your hard drive clean, destroying all your data.
Most viruses are developed by people of a destructive mindset either for their own sadistic amusement or to show their friends how clever they are. Occasionally they have a different purpose such as collecting your personal data and relaying it to their creator for ID theft or hacking into your systems. This could cost you even more than the loss of your stored data. Even if a virus is not destructive it is usually annoying, repeatedly displaying messages on your screen or making your computer less efficient and slower.
Most viruses can be detected and removed if you have good anti virus software. With new viruses being developed and released almost daily, it is important to keep your anti virus program updated, otherwise you may not know that you have a virus until it is too late. But even if you scan your system regularly, a fast-acting virus may have already inflicted some damage. Just as with human diseases, prevention is better than cure.