The definition files
The definition files list the various viruses, their type, and their footprints and specify how to remove them. More than 100 new viruses are found in the wild each month. An antivirus program would be useless if it did not keep up with all the new viruses. The engine accesses the definition files (or database), runs the virus scans, cleans the files, and notifies the appropriate people and accounts. Eventually viruses become so sophisticated that a new engine and new technology are needed to combat them effectively.
For an antivirus program to be effective, you must upgrade, update, and scan in a specific order:
1. Upgrade the antivirus engine.
2. Update the definition files.
3. Create an antivirus emergency boot disk.
4. Configure and run a full on-demand scan.
5. Schedule monthly full on-demand scans.
6. Configure and activate on-access scans.
7. Update the definition files monthly.
8. Make a new antivirus emergency boot disk monthly.
9. Get the latest update when fighting a virus outbreak.
10. Repeat all steps when you get a new engine.