Definition - What does Virus Signature mean?
A virus signature is a string of characters or numbers that makes up the signature that anti-virus programs are designed to detect. One signature may contain several virus signatures, which are algorithms or hashes that uniquely identify a specific virus. A large number of viruses may share a single signature, allowing a virus scanner to detect viruses it has never seen before.
Techopedia explains Virus Signature
Generic or heuristic detection are the two types of scanning that anti-virus software employs when looking for virus signatures. Generic detection is not as effective as heuristic scanning because it neglects to locate new virus signatures, but it is better at finding new viruses that have been developed from existing virus families.
Heuristic detection methods encompass more than 250,000 new virus signatures and are most effective for locating new virus signatures. New signatures are created each time a new virus comes out so that they can detect the viruses during scans. It is necessary to create the new signatures as the new viruses cannot otherwise be detected.
When the anti-virus vendor has tested the new signature, the vendor sends it out in the form of a signature update so that it correlates to the users’ anti-virus scanning capabilities. This may also include signature replacements, or the removal of prior signatures when they are no longer able to properly scan for the revised signature viruses. That is why computer experts advise users to always update their anti-virus scanners when vendors send out packets.