Graphical identification and authentication

GINA is a replaceable dynamically linked library that is loaded early in the boot process in the context of Winlogon when the machine is started.

Developers who implement a replacement GINA are required to provide implementations for a set of API calls which cover functionality such as displaying a "workstation locked" dialog, processing the secure attention sequence in various user states, responding to queries as to whether or not locking the workstation is an allowed action, supporting the collection of user credentials on Terminal Services-based connections, and interacting with a screensaver.

When the Winlogon process starts, it compares its version number to that which is supported by the loaded GINA library.

Windows XP introduced support for Fast User Switching, Remote Desktop and a more interactive, simplified and user-friendly full-screen logon.

One difference, however, is that GINA could completely replace the Windows logon user interface; Credential Providers cannot.