What is a scan engine?

What is a scan engine?
A virus-scanning engine is the program that does the actual work of scanning and detecting viruses,

while signature files are the “fingerprints” used by scan engines to identify viruses. New versions of a

scan engine are released for a number of reasons. New types of viruses or other malicious code, such as
spyware, may not be detected by the old engine. Updated scan engines also have enhanced scanning

performance and detection rates. Some vendors provide updates for both the scan engine and signature

files in a single file, while others provide them in separate files.