Pretty much anyone who uses the Internet today has heard of computer viruses and malware and understands that you need some kind of antivirus software to protect them from all the malicious files, scammers, and threat actors. On the other hand, most people do not have an under-the-hood understanding of how an antivirus protects your data and your computer. And truthfully, an under-the-hood understanding isn’t really necessary, but a basic understanding of the nuts and bolts of antivirus software (AV) is recommended, as it can help you decide what type of AV software you need.
A look at the purpose of AV software is a good place to start: AV software runs real-time scans and checks of your data and files in order to find and detect all types of malware. If any are detected, the antivirus software will remove, quarantine or delete it, depending upon your software settings.
Now a look at the how: There are essentially three detection methods used by AV software today. These include signature-based, heuristic-based, and behavioral-based detection. Signature-based detection looks for malware signatures, or the digital fingerprints of malicious files, and compares them to a signature database of known malware signatures. If a match is found, it indicates a virus. This detection method is extremely effective at detecting and eradicating known viruses, but in order for it to be effective, your AV software must receive regular updates. The database of known malware signatures changes whenever new malware signatures are discovered, so the AV software must have access to the latest database in order to be able to detect all known viruses.
To detect new and emerging threats, however, different detection methods are needed. Today, the best antivirus software use heuristics and behavioral detection for identifying emerging threats. Heuristics-based detection scans for malware by using a set of rules and algorithms to identify commands that might be malicious. Behavioral detection uses a different method and works by looking for files that are behaving suspiciously. Abnormal requests for access to files or processes, or significant increases in data usage are just two examples of suspicious behavior.
Thus, by using a combination of detection methods, AV software are able to detect all types of known and emerging malware including but not limited to ransomware, Adware, spyware, Trojans, worms etc.
Some AV software also have additional, more advanced features for detecting cyber threats such as browser protection and anti-phishing toolbars to protect against phishing emails and phishing sites, child filters to keep children from visiting inappropriate websites, and microphone and camera protection to keep your conversations private and to prevent hackers from spying on you.