Computer Virus

A virus is a piece of programming code usually disguised as a something else that causes some unexpected and usually undesirable event.A virus is often designed so that it is automatically spread to other computers.Viruses can be transmitted as attachments to an e-mail ,as downloads,or be present on a diskette or CD.The source of the e-mail,downloaded file,or diskette you've received is often unaware of the virus.Some viruses wreak their effect as soon as their code is executed;other viruses lie dormant until circumstances cause their code to be executed by the computer .Some viruses are playful in intent while others can be quite harmful,erasing data or causing your hard disk to require re formatting.It must be remembered that a computer virus does not spread on its own,rather it requires some carrier to transport it from one place to another.We send e-mail document attachments,trade programs on diskettes,or copy files to file servers.When the next unsuspecting user receives the infected file or disk ,they spread the virus to their computer,and so on.

Categories of Computer Viruses

There three broad categories of viruses are as follows:

• File Infectors
• System Infectors
• Macro Viruses

File Infectors

Some file infector viruses attach themselves to program files while some can infect any program for which execution is requested.When the program is loaded,the virus is loaded well.Other file Infector viruses arrive as wholly-contained programs or scripts sent as an attachments to an e-mail note

System Infectors

These viruses infect executable code found in certain system areas on a disk.They attach to the DOS boot sector on diskettes or the Master Boot Record on hard disks.A typical scenario (Familiar to the author) is to receive a diskette from an innocent source that contains a boot disk virus.When your operating system is running,files on the diskette can be read without triggering the virus.However,if you leave the diskette in the drive,and then turn the computer off or reload the operating system,the computer will look first in your A drive,find the diskette with its boot disk virus,load it,and make it temporarily impossible to use your hard disk.(Takes several days for recovery).This is why you should make sure you have a bootable floppy.

Macro Viruses

These are among the most common viruses,and they end to do the least damage.Macro viruses infect your Microsoft Word application and typically insert unwanted words or phrases.

Symptoms for a virus

Some common symptoms for a virus are as follows:

• The computer begins to run slowly.
• Unusual messages and graphics appear on your screen for inexplicable reasons.
• Music,not associated with any of the current programs,begins to play.
• Some of the program and/or data files have either been corrupted,or they have become difficult to locate.
• Unknown files or sub-directories has been created.
• The size/dates of executable files change automatically.
• The computer does not remember CMOS settings.
• The disk volume label has been changed mysteriously.
• The sizes of total and free memory are changed unexpectedly.
• The hardware devices begin to exhibit unusual behavior.

Anti-virus Software

An anti-virus software protects your computer from unexpected virus attack.Apart from protecting your system,anti-virus software performs the following tasks:

• Detects the name of virus and its type.
• Detects the name of infected file or folder and mentions the exact location of infected file or folder on your computer and removes the virus from the computer.
• Most of the anti-virus softwares come with Alert feature.This feature keeps a vigil on your computer and as soon as some virus-like activity is found,the alert featuredisplays a message box and alters the user.
• By changing the settings of anti-virus,you can instruct it to scan the computer on a regular basis.
• With regular updates,anti-virus software protects your computer from new viruses.

You can easily purchase an anti-virus software from market or can easily download free version of some anti-virus software from the website.But it si recommended that you purchase a complete and genuine copy of anti-virus software as it comes with future supports for your computer like updating your an anti-virus software against the latest virus threats and various additional features.the names of some popular anti-virus softwares are listed below.

NORTON ANTI-VIRUS

MCAFEE

SMART COP

SPYWARE

REGISTER MECHANIC