File created by Windows CardSpace, an application used to manage digital identities; contains personal or business information, such as names, addresses, and phone numbers; also contains a digital signature that identifies the individual or business.

Windows CardSpace cards enables users to have a "virtual ID" for safely signing onto websites. A single card can be used for accessing multiple websites. When sending a card to a website, personal information is not sent unless it is explicitly authorized by the user. Instead, only the digital signature is sent to identify the user. CardSpace cards may be issued from a managed card provider, such as a business or organization. These cards are referred to as Managed Information Card files. Companies use these to authenticate and validate entities within the company. CRD files are only usable by websites and other online entities that support Windows CardSpace cards. NOTE: CRD files were also used by older versions of Windows, prior to Windows 95. These files are in a different format than modern CRD files, but can still be opened by the AZZ Cardfile program.