COMPUTER VIRUS 

   What is computer virus ?

A computer virus is a program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves. All computer viruses are man-made. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.
Since 1987, when a virus infected ARPANET, a large network used by the Defense Department and many universities, many antivirus programs have become available. These programs periodically check your computer system for the best-known types of viruses.
Some people distinguish between general viruses and worms. A worm is a special type of virus that can replicate itself and use memory, but cannot attach itself to other programs

  What do computer viruses do?

Through the course of using the Internet and your computer, you may have come in to contact with computer viruses. Many computer viruses are stopped before they can start, but there is still an ever growing concern as to what do computer viruses do and the list of common computer virus symptoms. A computer virus might corrupt or delete data on your computer, use your email program to spread itself to other computers, or even erase everything on your hard disk.
Computer viruses are often spread by attachments in email messages or instant messaging messages. That is why it is essential that you never open email attachments unless you know who it's from and you are expecting it.
Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files.
Computer viruses also spread through downloads on the Internet. They can be hidden in illicit software or other files or programs you might download.
To help avoid computer viruses, it's essential that you keep your computer current with the latest updates and antivirus tools, stay informed about recent threats, run your computer as a standard user (not as administrator), and that you follow a few basic rules when you surf the Internet, download files, and open attachments.
Once a virus is on your computer, its type or the method it used to get there is not as important as removing it and preventing further infection.

 Antivirus protection and how to avoid viruses

Is your computer running more slowly than usual? Does it stop responding, freeze often, or display other odd behavior? It might have a virus. Fortunately, if you update your computer regularly and use antivirus software, you can help permanently remove unwanted software and prevent it from being installed in the first place.

  Steps to be taken for Virus Detection and Prevention

• Do not open any files attached to an email from an unknown, suspicious or untrustworthy source.
• Do not open any files attached to an email unless you know what it is, even if it appears to come from a friend or someone you know. Some viruses can replicate themselves and spread through email. Confirm that your contact really sent an attachment.
• Do not open any files attached to an email if the subject line is questionable or unexpected.
• Delete chain emails and junk email. Do not forward or reply to any to them. These types of email are considered spam - unsolicited, intrusive messages that clog up the inboxes and networks.
• Do not download any files from strangers.
• Exercise caution when downloading files from the Internet. Ensure that the source is a legitimate and reputable one. Verify that an anti-virus program checks the files on the download site.
• Update your anti-virus software regularly. .
• Back up your files on a regular basis. If a virus destroys your files, at least you can replace them with your back-up copy. You should store your backup copy in a separate location from your work files, one that is preferably not on your computer.
• When in doubt, always err on the side of caution and do not open, download, or execute any files or email attachments. Not executing is the more important of these caveats. Check with your product vendors for updates for your operating system, web browser, and email.