What is a Virus?

A virus is a program of piece of code that is installed and runs on a computer without the users knowledge. Viruses cannot install themselves, they must be run by a human, mostly likely from an executable file. Viruses can use up system resources, replicate themselves, allow a user remote access to the infected computer, as well as destroy personal data, hardware and software. Many viruses are spread via email. Viruses are different than spyware.

There are many different types of viruses.
Boot Virus - affects the boot sector of a floppy or hard disk (hard drive). The boot sector is a crucial part of the system since it holds information about how a computer boots (is started) up. A boot virus does not infect files, it infects the disks on which they reside.

Macro Virus - enter a system by exploiting vulnerabilities in macros. Microsoft Word (.doc file extension), Excel spreadsheets (.xls file extension) and many more...

Polymorphic Virus - changes itself (actually, encrypts, or encodes itself) so as to be hidden from scans. When it is going to deliver it's damage it decrypts, does what it is designed to do and goes back into hiding.

Resident Virus - hides in RAM memory, from where it can control all operations of the system.

Trojan Horse - is a master of deception. It usually hides in software that appears to be a legitimate application. Once opened by the user a Trojan can do anything from delete files, and destroying system information to less malicious things as making your cd rom open and close and changing your desktop icons around. Trojans are famous for creating a backdoor in the infected computer. This backdoor allows users remote access which can be used to control the computer for whatever use the controller wishes. Trojans do not reproduce by infecting other files, which is one of the major differences between a trojan and a worm. One of the 'newer' types of Trojans include ransomware .


Worms - are a sub-class of viruses. They spread from computer to computer and have the ability to move from computer to computer across networks without the help of a human. A worm exploites vulnerabilities in software and operating systems using existing files and transport systems already in place on the infected machine. One of the most dangerous thing about worms is their ability to replicate. An infected system could be used to not only send one copy of the worm out onto the Internet but possibly thousands of copies. In the meantime, draining the infected computer of valuable system resources.

There many more classicifations of computer viruses. These are just a few to touch on.


How do I know if my computer is infected? What are the signs of a virus?

Sometimes you can't even tell you have a virus! That's part of the problem. But other signs include the following:

system reboots? - Does your system spontaneously restart? This could be a virus or, if could be a legitimate problem with other hardware or software. That is one of the tricks of viruses. Sometimes they mimic 'normal' system problems therefore leaving the user unware of the problem.

system slowdowns? - Has your system mysterious begun to get slower and slower as time passes? You might have a virus? or maybe not? It can't hurt to check!

computer will not boot (start)? - You might have a virus. Try starting in Safe Mode (press the F8 key when booting), if you can boot all might not be lost.

see strange messages appearing when you turn on your computer? - I don't mean strange system generated messages, they have their own level of strangeness, I mean something that seems out of place - something not quite right.

files disappearing? - Was there a program, or file on your computer one day but not there the next and you are the only user? You might have a virus.

These are just a few signs that your computer could be infected by a virus . Since there are so many no-cost versions of antivirus software available there is no excuse for a home user to not have antivirus software installed on their pc.


How can I prevent viruses from getting on my PC?

Install antivirus software before you get infected

Install a software firewall - a firewall acts as a barrier between your computer and the Interent.

Keep Microsoft Windows Up-To-Date - with Windows Update. Microsoft often releases software patches which you can download and install to help prevent malicious software from being installed on your PC.

Stay away from questionable Websites! - you know what I am talking about!

Use a superior Web Browser - such as Mozilla Firefox