Vulnerability scanning is the process of scanning software and systems for known vulnerabilities.
A vulnerability scanner will maintain and refer to a massive database of known vulnerabilities in order to compare and classify anything it finds. Vulnerability scanners work by scanning for known entry points (A field on a form on a webpage for instance) and testing what would happen if known exploit code were sent to it. Another way to look at it is like a conversation, where the scanner โtalksโ to the software and then measures its response against known responses of vulnerable systems.