Antivirus software are different use. I teach representative software.
pattern matching style
It compares the update file and virus file. It checks virus list so it takes effect the known virus. But it is weak to unknown virus.
check sum style
It searches a file before changes and after changes. It deals with unknown virus but it can’t stop virus.
heuristic style
It checks sign of changing file. So strange file report on your computer. But it sometimes mistakes normal program danger program.
These program needs to adapt your computer. It has chemistry to your computer. You should install trial version and check chemistry.
