When you use Forefront Endpoint Protection, it is important to have up-to-date virus and spyware definitions. Definitions are files that act like an ever-growing encyclopedia of potential software threats. Endpoint Protection uses definitions to determine if software that it detects is a virus, spyware, or other potentially unwanted software, and then to alert you to potential risks. To help keep your definitions up to date, Endpoint Protection works with Microsoft Update to install new definitions automatically as they are released. You can also set Endpoint Protection to check online for updated definitions before scanning. For information about keeping your definitions up to date and how to download the latest definitions manually, see How do I keep virus and spyware definitions up to date?.