An anti-virus, otherwise spelled as antivirus, is a security application or program feature that's used to remove, detect, and prevent the proliferation of malicious software into your system, which may include Trojan horses, worms, viruses, botnets, and so on. This type of protective software could also be employed to thwart and eliminate spyware, adware, and practically any program that's viewed as a nuisance to the user's computing experience regardless if it's intentionally programmed to do so or not.
A multitude of assorted methods are usually employed by an anti-virus whenever it accomplishes its malware-related tasks. For instance, this type of security tool may use signature-based detection, which involves looking for known malicious strings within an application's programming code.However, it's very possible for a user to be attacked by a new form of malware where no identifiable patterns or signatures exist (otherwise known as zero-day threats). Ergo, it's always the prerogative of both the anti-virus program and the user to get the latest virus definitions and updates.
For added protection, it'd also be prudent to keep yourself updated in regards to the latest threats presently plaguing the worldwide web through IT security websites found online as well as email updates from the anti-virus vendor that sold you your anti-virus program. A tech-savvy user would never merely rely on a propriety or freeware anti-virus application when protecting his machine; good user habits and a well-updated security application should go hand-in-hand in battling against the malware menace.
New threats that have not been identified and included in the virus and malware definitions of your anti-virus software can also be mitigated via heuristics-based anti-virus programs. In fact, the heuristic approach known as generic signatures was specifically developed to expose new viruses or existing malware variations by looking for even the slightest hint of malicious code (and its respective variants) in files.The most advanced anti-viruses in the market could even predict what an infected file would do if it's allowed to execute via sandbox emulation, which helps a lot in analyzing an infection's threat level without necessarily letting it loose on an actual system. If the emulated file does anything remotely dangerous inside the sandbox, it would then be dealt with accordingly.