What is Cardfile (.CRD)?
Cardfile is a utility included with previous versions of Microsoft Windows that allows users to save information in a series of simulated 'flash cards'. It was integrated into Windows versions from 1.0 to Windows 95. Cardfile was intended to allow users to store contact information similar to a Rolodex, but has been largely replaced by email clients that also store contact information.
Cardfile was included in early versions of Windows, starting with Windows 1.0, to simulate a Rolodex containing index cards. Its primary use, as with the Rolodex, is for storing contact information such as names, phone numbers, and email addresses. Cardfile uses the .CRD extension. The increasing use of e-mail led to Cardfiles' demise.
The last versions of Cardfile for Windows 95, ME, and NT came out around the same time that office e-mail became common. Email clients like Outlook also store contact information. this seems to be the reason why the later versions of Cardfile were only available as an optional installation and not included with Windows by default. Even then, the program still has some nostalgia and some users have developed free replacements.