User Profiles
In a standard Windows NT system, interactively logged on users are given a profile. A profile is a registry hive that is tailored to that particular user. It is typically used to save user-specific information, such as screen appearance (colors, border widths, and so on), mouse click speeds, whether there is a screen saver, and whether or not it is secure, and so on. This profile, referenced using the special registry key HKEY_CURRENT_USER, is loaded by Winlogon during the interactive boot process.
The interface between Winlogon and GINA DLLs includes information passed back from GINA that allows Winlogon to locate and load the logged on user's profile.