They are computer programs that attempt to identify, neutralize or eliminate malicious software.
The term "antivirus" is used because the earliest examples were designed exclusively to combat computer viruses; however most modern antivirus software is now designed to combat a wide range of threats, including worms, phishing attacks, rootkits, Trojans, often described collectively as malware.
Antivirus scanning software, or a virus scanner, is a program which examines all files in specified locations, the contents of memory, the operating system, the registry, unexpected program behavior, and anywhere else relevant with the intention of identifying and removing any malware.
Typically two different approaches are used to identify malware, often in combination, although with an emphasis on the virus dictionary approach.
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