A virus checker or Anti-Virus Software will scan files and check for traces of a virus and is then able to remove the virus.

Anti-virus software works in two modes: stand-alone and memory resident. In stand-alone mode the software works like any other program. You start it and point it at a file, directory or disk to check the files for viruses.

In memory-resident mode the anti-virus software stays running on your system at all times. Whenever a file is used the software will check it for viruses. As well as checking files, most anti-virus software will also check e-mails and web pages.