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Аntivirus software consists of computer programs that attempt to identify, thwart and eliminate computer viruses and other malicious software (malware).

Аntivirus software typically uses two different techniques to accomplish this:

Most commercial antivirus software uses both of these approaches, with an emphasis on the virus dictionary approach.

Historically, the term antivirus has also been used for benign computer viruses that spread and combated malicious viruses. This was common on the Amiga computer platform.

Approaches

Dictionary

In the virus dictionary approach, when the antivirus software examines a file, it refers to a dictionary of known viruses that the authors of the antivirus software have identified. If a piece of code in the file matches any virus identified in the dictionary, then the antivirus software can take one of the following actions:

To achieve consistent success in the medium and long term, the virus dictionary approach requires periodic (generally online) downloads of updated virus dictionary entries. McAfee - Computer Anti-Virus Software and Internet Security For.