Antivirus programs are constantly becoming more powerful and adapting to the new technologies used by viruses. If they are not to become obsolete, they must be able to detect the new viruses that are constantly appearing. To do this, they have what is called a Virus Signature File. This file contains the information needed to identify each virus, making it possible to detect them and take the appropriate action. The action of adding the latest version of this file (and others) is known as updating.