A computer virus is some sort of malicious code that replicates itself and moves from one computer to another through a network. They spread like an epidemic and infect other computers causing loss of data and sluggish performance.

There are several ways for viruses to gain access to your computer some of which are downloading infected files and attachments from the internet, installing pirated and cracked programs, storage devices like flash drives, external hard drives and CD/DVD. These are just a few ways a computer can be infected by a virus.

When a virus infects a computer it is not only the computer that is infected that is at risk, all other computers that are connected on same network can be infected. The risk increases manifold if the computers do not have an updated antivirus installed.

Most of the latest anti viruses have an active shield program built into it. These shields monitor the incoming connections to your computer and scan them to detect any malicious code that might try to pass through and infect the computer. They also scan the websites you visit by monitoring the cookies and files that they install on your computer. But all of this would work only if the antivirus is updated and ready to tackle any viruses.

If after all of this your computer does have the misfortune of being infected by a virus you can try and get rid of it.

You should run a complete virus scan on your computer and not disturb it; it anyways runs in the background. Once the scan is completed the antivirus would present a report and let you know if your computer is infected. If it is you can choose to quarantine the virus or delete it completely. Quarantine means to isolate the file, because there is a possibility that any other program requires the file to run.

You can also choose to completely delete the file that is infected by the virus.

However there is a new generation of viruses that can escape being detected even by an updated antivirus. These viruses pretend to be a file that is part of the operating system. These viruses can be detected by running what is called a boot time scan. A boot time scan runs before the operating system loads and thus can detect these viruses and delete them.

If these steps do not work you should back up all your important data and reformat the computer which involves totally wiping out the hard drive and reinstalling your operating system. Once this is done the first program that you should install is the antivirus and then update both the operating system and the Antivirus. Make sure you scan the files you have backed up before transferring them back to your hard drive.