Most people have heard of computer viruses and know that they can do significant damage to our computers. Not only should you be aware of what viruses are, but you should also know why they happen and how to keep them at bay.

A computer virus is a program or piece of code that is loaded onto your computer without your knowledge or permission. Some viruses are merely annoying, but most viruses are destructive and designed to infect and gain control over vulnerable systems. A virus can spread across computers and networks by making copies of itself, just like a biological virus passes from person to person.

Where a PC virus comes from

Viruses are usually hidden in a commonly used program, such as a game or PDF viewer, or you may receive an infected file attached to an email or from another file you downloaded from the Internet. As soon as you interact with the file (run the program, click on an attachment or open the file), the virus runs automatically. The code can then copy itself to other files and make changes on your computer.

How to recognize a virus

Your Internet connecting might be slow or non-existent. It's common for your antivirus and/or firewall protection to disappear or be disabled. Computers infected by viruses are even capable of acting on their own, executing actions without you knowing.

How to remove a virus

Remove all temporary files and run a virus scan using antivirus software. If any viruses are detected, delete them.

How to prevent viruses

• Avoid programs from unknown sources.
• Don't open attachments from unsolicited email or in Facebook.
• Only download apps from Google's official Android Market.
• Secure your phone with Avast Free Mobile Security.

Protect yourself against viruses

There is no better way to recognize, remove and prevent viruses than to use an antivirus tool, and the best anti-virus tool is Avast.