Configuration file that contains setup information for Windows NT and XP; contains parameters referenced during the Windows operating system installation process; includes the target path, user data, OEM status, display resolution, network settings, and other information.

The default name for the primary Windows SIF file is "winnt.sif." If this file cannot be found by the Windows installer, the installation process may not continue. If the SIF file is missing, the optical drive or installation disk may be faulty and should be cleaned or replaced.

SIF files are also referred to as "answer files."