PC Security: How does anti virus software work?
How do anti virus programs work?
Anti virus software is probably the most important program you have installed on your computer, but do you really know how it works? Most PC owners purchase or install an anti virus program and forget about it. But if you don't understand how anti virus software works, you might be leaving yourself prone to catching a virus.
Know thy virus enemy
Real-Time anti virus protection
Most anti virus programs use virus signature scanning to detect viruses on your computer. This means that the anti virus program has a list of known virus signatures in it's database, and checks this database each time your PC opens or access any file. A virus signature is a particular pattern of 'bits' or information contained in a virus that appears in no other file or program in the world, except for that virus. A signature is like a digital fingerprint of the virus. A good anti virus program will have a database of approx 20,000 to 60,000 known viruses. Because it can take a few milliseconds to screen every file through a list of many thousands of virus signatures, it is common for an anti virus program to make your computer run a little slower after installation. One measure the effectiveness of an anti virus program is how much it does, or does not slow down a computer after installation.
On demand virus scanning
Another type of virus protection is on demand scanning. Unlike real-time virus protection, on-demand only checks for viruses when manually initiated. Because you have no protection against a virus between on-demand virus scans, real time anti virus is a better method of protecting your PC against catching a virus, however a good antivirus program will support both methods of virus scan.
Anti virus protection is a constant game of keeping up
It is estimated that between 100 and 500 new viruses are released into the wild (spreading via the internet) every day. Because of this constant influx new viruses, it is extremely important to update your anti virus program's signature database as often as possible. Virtually all commercial anti-virus programs today will update themselves over the internet automatically every month, or more often. Good anti virus programs will even update themselves whenever a particularly dangerous virus is released onto the internet. Most free or low-cost anti virus programs require manual virus signature updates and are usually updated much less often than standard commercial anti virus programs. Because of the manual intervention required by many free anti virus programs, and the potential lack of signature updates, it is usually safer for your computer to purchase a good anti virus package. Even the best anti-virus programs rarely cost more than $49 - well worth the investment if you value your time, files, photos and other data in your PC.
Real-time and on-demand scanning are the best combination
Because real-time virus protection only protects your PC from virus threats since the last virus signature update, it is possible for a new virus to be released, get into your PC, and go totally unnoticed by your antivirus software. This is why even with a good antivirus program it is important to practice safe computing. To help catch any viruses that may have "slipped through the cracks" between virus signature database updates, it's a good idea to run an on demand virus scan at least one time every month or two. Most commercial anti-virus programs will remind you to perform on-demand scans regularly, however many free or discount anti virus programs may not.
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