What is a computer virus?

Software that detects, repairs, cleans, or removes virus-infected files from a computer.

A computer virus essentially acts like a biological virus and usually gets into a computer system through unsolicited email.

Antivirus software is a computer programs that attempts to identify, neutralize or eliminate malicious software. Most modern antivirus software is now designed to combat a wide range of threats, including worms, phishing attacks, rootkits, trojan horses and other malware.

Antivirus software typically uses two different techniques to accomplish this:

• Scanning files to look for known viruses that are found in a virus dictionary.
• Looking for suspicious behavior from a computer program which might indicate infection.

Most commercial antivirus software uses both approaches, although there is an emphasis on the virus dictionary approach.

In the virus dictionary approach, the antivirus software first looks at a file it then refers to a dictionary of known viruses that have been identified. If part of the code in the file matches any virus identified in the dictionary, the antivirus software can then take one of the following actions: 1: Attempt to repair the file by removing the virus itself from the file 2: Quarantine the file (so that the file is inaccessible to other programs and the virus can no longer spread) 3: Delete the infected file

To achieve success over time, the virus dictionary approach requires users to download updated virus dictionary entries.

Although the dictionary approach can effectively contain virus outbreaks, virus creators always try to stay a step ahead of such software by writing their viruses with encrypted parts or otherwise modify themselves as a method of disguise, so that it does not match the virus's signature in the dictionary.

The suspicious behavior approach, doesn't attempt to identify known viruses, instead it monitors the behavior of all programs. If a program tries to does something that it is not supposed to the antivirus software can flag this behavior as suspicious and then alert the user and ask what to do.

The suspicious behavior approach unlike the dictionary approach provides protection against brand-new viruses that do not yet exist in any the known virus dictionaries. However, it can also sound a large number of false positives, resulting in the users becoming desensitized to all the warnings.

Some virus scanners can also warn a user if a file is likely to contain a virus based on the file type.

Sometimes antivirus software can considerably reduce a computer's performance. Some users may disable the antivirus protection to overcome the performance loss, and increase their risk of infection. For maximum protection your antivirus software should to be enabled at all times.

Sometimes it is necessary to temporarily disable the virus protection when installing major updates. Having antivirus protection running at the same time as installing a major update may prevent the update installing properly or at all.

Some antivirus programs are actually spyware masquerading as antivirus software. It is best to double-check that the antivirus software which is being downloaded is actually a real antivirus program.