Antivirus has been marketed for a long time as a commodity like a toothbrush, detergent or car. Although they are popular, antiviruses are not without faults.
Antivirus software simply cannot keep up with the diversity and variety of new malwares released every single day. It is an arms race, and far from all antivirus programs available on the internet actually offer an overall security level that is close to 100 100%.
Another problem is that viruses and Trojans can alter the software on your computer so that it is unable to detect them properly. This could be because the virus alters the settings of your antivirus program or because it is able to create false positives through exploiting one of its own functions or features.
There are also many instances when the antivirus software is unable to recognize files, even when they are clearly infected with malware. This happens because the anti-virus hasn’t had the chance to add the specific file to its database. To achieve this, it has to examine the file and analyze its contents with malicious files already in the database of the antivirus. This is a long and resource-intensive process. The more time it takes is, the less accurate the detection. The antivirus must also install interceptors that look at system events deep within the protected computer kernel in order to relay the information to its engine.