When you type the phrase "computer virus" in Google search engine, it will display 49,100,000 results. This phrase is very much familiar nowadays. As a computer user or techie person, you must know them better.

Let me give you an overview of what is a virus, how it was started, and how to prevent it.

Computer virus can be defined as program that is "intentionally created" that is capable of duplicating itself, to spread in your computer programs, files and even on your removable storage. This can be transferred through the internet, network connection, or even through the use of removable disk. The worst it can totally damaged your hard disk - corrupt your entire files. The term computer virus is commonly used to refer to any malicious or unwanted code or software to name some like worm, Trojans, adware, spyware and malware. Also, there are some viruses that can be easily noticed and there are some which are not.

In computing, the first computer virus ever detected was Creeper Virus in 1970s which is capable of duplicating the program on ARPANET. In 1986, the first PC boot sector virus was created. Afterwards was the development of the virus for removable disk specifically floppy disks.

In 1980s was the development of virus that was attached to the duplicated pirated software installer. Macro viruses were created in mid-1990s to infect documents and spreadsheets created through Microsoft Word and Excel.

At present, virus can spread through the web and instant messenger. I have this experienced when my contact friends in Yahoo received an email containing virus and easily infect their computers.

Do you know the virus infection scheme? For computer virus to duplicate itself, it should be allowed to execute the code and write it on the memory. This can only be done after you run a program that contain a virus or after you restart the computer. This is the reason why most viruses join themselves to an executable file. When the computer starts the executable file, the virus code will also be started. We have two types of virus the residents and non-residents.

Non resident virus finds a new file or program to infect. On the other hand, resident virus loads a duplicate into the memory and guarantee that this will load together with the operating system every time it performs a tasks.

There are some virus designed to perform actions like displaying messages or web page on your screen (if you are connected in the Internet), lessen your memory and disk space, and modify, overwrite or damaged your data (like converting your word files to executable files).

But take note, you can protect your computer against viruses by simply doing some practical tips.

1. Try to use a secured operating system like UNIX. If you opt to use Windows, make sure that you enabled the Macro Virus Protection in all the Microsoft application programs.
2. Avoid opening or starting any program or email from unknown users
3. Purchase a virus protection program. Make sure that it is always updated.

Try to follow these simple steps to maintain a virus-free computer.