These days it is not safe to use your computer without installing one of the programs for virus protection. Threats can appear from anywhere. They are certainly present all over the internet, but can just as easily be caught by inserting an infected disc into your system.
A virus is a piece of software written deliberately to enter your computer and damage your data. It might even prevent your computer from starting up. Typically, it attaches itself to another program and replicates itself as it tries to infect as many files as possible.
Examples of such software are macro viruses and logic bombs. Logic bombs are triggered to do damage when a specific program is executed. Macro viruses infect documents run by programs that use macros.
There are many different types of viral infection, but probably the best known are worms and Trojans. Worms use computer networks and security holes to reproduce independently, without needing to attach themselves to another piece of software. Trojans are destructive programs and disguise themselves as safe ones. They don’t reproduce themselves, but can crash your system or erase files on the hard drive.
These infections can enter your system in three ways. Firstly, via a disk drive, when you insert an infected disk or CD, secondly, via files downloaded from the internet, and thirdly as an email attachment. Whichever way they get in, they can cause untold havoc and damage to your system and data.
Installing anti-virus software can prevent all these things happening to you. There are many different ones available on the market, and you need to study their specifications to decide which is the right one for you. While you can get expensive ones that appear to cover every eventuality, you can also download free ones which, while not being as comprehensive, can certainly do a more than adequate job for most home users. I am glad that all the spyware, adware and Trojan viruses on my computer are all gone now all thanks high quality software which I downloaded.