Antivirus software is used to prevent, detect, and remove malware, including computer viruses, worms, and trojan horses. Such programs may also prevent and remove adware, spyware, and other forms of malware. This page talks about the software used for the prevention and removal of such threats, rather than computer security implemented by software methods.
A variety of strategies are typically employed. Signature-based detection involves searching for known patterns of data within executable code. However, it is possible for a user to be infected with new malware for which no signature exists yet.
To counter such so-called zero-day threats, heuristics can be used. One type of heuristic approach, generic signatures, can identify new viruses or variants of existing viruses by looking for known malicious code in files.
Some antivirus software can also predict what a file will do if opened/run by emulating it in a sandbox and analyzing what it does to see if it performs any malicious actions. If it does, this could mean the file is malicious.
