Computer Viruses and Antivirus Software

What is a Computer Virus, and Why is it Called a Virus?

Before understanding what a computer virus is, it is necessary to understand what a virus in when it occurs in a living form (such as a human body, an animal, or a plant).

A virus is a small organism that is only able to reproduce itself within another living cell or body. It is typically harmful to the cell or body in which it lives, and is the cause of many illnesses and diseases. The word virus comes from Latin, and literally it means “poison.”

So basically it is a “poison” able to reproduce itself within another cell or body. An example of an illness caused by a virus is the flu.

How does this relate to computers?

Well basically, a COMPUTER VIRUS is a harmful computer program which will damage files or your computer, and which is able to duplicate and spread itself within a computer or computer network. Usually the computer virus is hidden within a program, file or document.

Perhaps even more dangerous is the fact that viruses can also spy on you and steal your private information. They can collect your passwords, bank data, and credit card numbers. And the creators of the viruses can you this data to go into your private accounts, steal money, buy things in your name, and more. (When people steal your personal information and pretend to be you, this is called “identity theft.”)

Criminals, or somewhat talented idiots with nothing better to do with their time, create computer viruses and spread them to other people’s computers. Sometimes the sole purpose of this activity is to create trouble and damage. But in some cases, the purpose is identity theft, spying, and taking money from your accounts.

Similar to a common virus like the flu (which spreads from person to person), the computer virus has the ability to spread and “infect” other computers, files or documents.

A computer virus can spread itself through files documents such as word documents, spreadsheets, emails, computer programs etc. It can spread itself through the Internet, Local computer networks as well as through removable storage devices such as memory sticks and floppy disks.

Because it is hidden, it is hard to detect, and can it can be spread to other computers, unknowingly, by the computer user.

What exactly does a computer virus do?

A computer virus works similarly to a regular virus like (the flu) that makes a person sick, A computer virus will make your computer “sick”.

What a virus will do to your computer depends on what it is programmed to do. Some can be very harmful, while others are made to simply annoy. A wide variety of names have been made up, in order to describe different types of computer viruses.

Some examples are as follows:

Macro Viruses

A MACRO is a computer instruction that tells the computer to take a series of actions. This is a very useful tool. It can, however, also be used to perform destructive actions.

Because of its nature, this type of virus is very easy to hide in files or documents. Macro viruses infect files that are created in certain programs, such as Microsoft Office documents, Word documents, Excel spreadsheets, PowerPoint presentations, and so forth.

The key point to remember is that the document being used in this case allows special actions; such as showing a picture, performing a calculation, playing a sound, etc.

One of the first macro viruses written was for Microsoft Word. It was discovered back August 1995. Today, there are thousands of macro viruses in existence, using many different types of programs.

This kind of virus is easily spread across a Local Area Network (a Network is a group of several computers which are connected in an office or home) or even over the Internet. Usually it spreads through shared drives and folders. Once it infects a system, it looks for other computers on the network, and tries to infect those.

(For more information on Macro Viruses, see the page here.)

Email Viruses

An email virus could be a form of a macro virus that spreads itself to all the contacts located in your email address book.

It automatically uses the addresses to send emails from your computer. If anybody opens the attachment of the infected mail, the virus spreads to that persons address book contacts, and then sends itself to all those contacts as well.

One can infect one’s computer with an email virus even by just previewing the infected email.

(For more information on Email Viruses, see the page here.)

Trojan Horses

A Trojan Horse is a computer file which seems to be a useful, needed and wanted file. But in actual fact, it is a harmful file.

A Trojan horse appears to be doing something innocent, like showing a picture inside an e-mail, or installing a screen saver or other program. But in fact it is also doing something else, such as erasing files, or secretly sending information stored on your computer (such as passwords and other personal information) to the hacker who wrote it.

(For more information on Trojan Horses, see the page here.)

For more information about other types of harmful software, see the links on the right-hand column of this page.)

How to Deal with Computer Viruses

There are many ways in which a virus can infect your PC. But regardless of weather it is a harmful virus or an annoying “practical joke,” it is dangerous to let one loose on your system, and it should be dealt with immediately.

Whether you are connected to the Internet or not, it is safest to have an antivirus program installed on your computer. If you are connected to the Internet, it is basically a must.

Types of Antivirus Programs

There are two types of anti virus programs. Both do more or less the same thing, but use different methods. Both types of programs are constantly on the lookout for viruses on your computer, but they do so in different ways.

The first one keeps a list of known viruses and virus types, called “virus definitions.” This list of virus definitions is called a virus library. It constantly looks through your computer, checking to see if anything coming into your computer is a virus. It does so by comparing all things coming in with what it has stored in its “virus library”.

Any file, document, or program coming into your computer is inspected and compared to this library to see if it matches any of the “virus definitions.” One disadvantage of this system is that if a new virus comes out that is different than the viruses stored in your library, this type of antivirus program will not detect it and will allow it onto your computer.

When using such a program, it is important to have a subscription, and to be connected to the Internet, so that your virus definitions are constantly updated. New viruses come out every day. If you choose such a program, one of the things to check for is how often the virus definitions are updated. This will play an important role in keeping your computer safe.

The second type of anti-virus program is called a HEURISTIC program. “Heuristic” means “learning by discovery or trail and error.” It comes from the Greek word “heuriskin,” which means “to discover”.

In other words, the program is capable of discovering new viruses not already known. It is written in such a way that it is able to learn and discover new viruses, without having to refer to a library. This program will most likely also have a library of virus definitions. But in addition to detecting already known viruses, it is able to detect new viruses, and is therefore a more secure program.

Will My Antivirus Program Drain my Computer of Energy?

One final thing to take into account, when choosing an anti-virus program, is how much computer power your anti-virus program uses. It is all fine to have the biggest antivirus program in the world, but that might not leave much computer power left for you to run your other programs. This is an important factors for you to take into account. Otherwise, you may run into a situation where, instead of viruses slowing your computer down, your antivirus program is slowing your computer down!

Some of the common Antivirus programs are as follows:

Kaspersky Antivirus

Trend Micro Antivirus

Norton Antivirus by Symantec

McAffee Antivirus

Panda Antivirus

For reviews of these antivirus programs and my own experience with them, please see the post here:

Reviews of Antivirus Programs

Useful Tips for Avoiding Computer Viruses

1. Only open email or Instant Message attachments that come from someone you know and trust, and that you are expecting.

2. Have email attachments scanned by an internet security program before opening them.

3. Delete any unwanted or suspicious messages without opening them.

4. Do not click on Web links emailed to you by someone you do not know

5. If a person on your Instant Message “Buddy list” (or “Friends List,” etc.) is sending strange messages, files, or web site links, end your Instant Message session at once.

6. Scan all files with an Internet Security program before moving or copying them to your computer. To do this, right-click on the document. If you have an anti-virus program installed, an option like “scan for viruses” will appear.

7. Only copy, transfer or download files from a well known source.

8. Keep your virus definitions up to date and use an Anti-Virus Program which does frequent updates.

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